Wireless communications system, base station, terminal, and process method

ABSTRACT

A wireless communications system includes a base station configured to switch a first state of storing to control information transmitted to a terminal, a value instructing a transmission power of the terminal, and a second state of storing to the control information, a value instructing a transmission count of multiple transmissions of a same data by the terminal; and the terminal configured to switch a third state of adjusting the transmission power based on the value stored to the control information received from the base station in the first state, and a fourth state of adjusting the transmission count of multiple transmissions of the same data by the terminal, based on the value stored to the control information received from the base station in the second state.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication PCT/JP2014/059372, filed on Mar. 28, 2014, and designatingthe U.S., the entire contents of which are incorporated herein byreference.

FIELD

The embodiments discussed herein are related to a wirelesscommunications system, a base station, a terminal, and a process method.

BACKGROUND

Use of plural transmission time intervals (TTIs) for transmittinginformation related to a single hybrid automatic repeat request (HARQ)process is conventionally known (for example, refer to JapaneseLaid-Open Patent Publication No. 2013-9401).

Further, it is known that when downlink control information controllingplural uplink data transmissions is detected and the downlink controlinformation instructs disabling of uplink data transmission, uplink datatransmission is disabled and ACK is set in a HARQ process correspondingto uplink data transmission (for example, refer to Japanese Laid-OpenPatent Publication No. 2012-165471).

Further, according to a known technique, a TTI transmission bundlehaving transmission time mapped on voice over IP (VoIP) arrive time isprocessed, the bundled TTI transmission is processed withoutacknowledgement, and indication that the bundled TTI transmission wascorrectly received is given (e.g., refer to PublishedJapanese-Translation of PCT Application, Publication No. 2013-520140).

Under Long Term Evolution (LTE), transmit power control (TPC) of anuplink is under consideration. Further, under LTE, TTI bundling where aterminal successively transmits the same data by uplink is underconsideration.

SUMMARY

According to an aspect of an embodiment, a wireless communicationssystem includes a base station configured to switch a first state ofstoring to control information transmitted to a terminal, a valueinstructing a transmission power of the terminal, and a second state ofstoring to the control information, a value instructing a transmissioncount of multiple transmissions of a same data by the terminal; and theterminal configured to switch a third state of adjusting thetransmission power based on the value stored to the control informationreceived from the base station in the first state, and a fourth state ofadjusting the transmission count of multiple transmissions of the samedata by the terminal, based on the value stored to the controlinformation received from the base station in the second state.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a diagram depicting one example of a wireless communicationssystem according to a first embodiment;

FIG. 1B is a diagram depicting one example of signal flow in thewireless communications system depicted in FIG. 1A;

FIG. 2A is a diagram depicting one example of a wireless communicationssystem according to a second embodiment;

FIG. 2B is a diagram depicting one example of TTI bundling in uplinkunder LTE;

FIG. 3 is a diagram depicting one example of a changing of a TTI bundlesize;

FIG. 4A is a diagram depicting a first example of a UL grant bitmap in atransmission power control mode;

FIG. 4B is a diagram depicting a first example of a UL grant bitmap in aTTI bundle size control mode;

FIG. 5A is a diagram depicting a second example of a UL grant bitmap inthe transmission power control mode;

FIG. 5B is a diagram depicting the second example of a UL grant bitmapin the TTI bundle size control mode;

FIG. 6A is a diagram depicting one example of a transmission powercontrol command setting method in the transmission power control mode;

FIG. 6B is a diagram (part 1) depicting an example of the transmissionpower control command setting method in the TTI bundle size controlmode;

FIG. 6C is a diagram (part 2) depicting an example of the transmissionpower control command setting method in the TTI bundle size controlmode;

FIG. 7 is a sequence diagram depicting one example of operation of thewireless communications system according to the second embodiment;

FIG. 8A is a diagram depicting one example of an eNB according to thesecond embodiment;

FIG. 8B is a diagram depicting one example of signal flow in the eNBdepicted in FIG. 8A;

FIG. 8C is a diagram depicting one example of hardware configuration ofthe eNB;

FIG. 9A is a diagram depicting one example of the UE according to thesecond embodiment;

FIG. 9B is a diagram depicting one example of signal flow in the UEdepicted in FIG. 9A;

FIG. 9C is a diagram depicting one example of hardware configuration ofUE;

FIG. 10A is a flowchart (part 1) of an example of processing by the eNBaccording to the second embodiment;

FIG. 10B is a flowchart (part 2) of an example of processing by the eNBaccording to the second embodiment;

FIG. 10C is a flowchart (part 3) of an example of processing by the eNBaccording to the second embodiment;

FIG. 11A is a flowchart (part 1) of an example of processing by the UEaccording to the second embodiment;

FIG. 11B is a flowchart (part 2) of an example of processing by the UEaccording to the second embodiment;

FIG. 11C is a flowchart (part 3) of an example of processing by the UEaccording to the second embodiment;

FIG. 12A is a diagram depicting another example of changing of the TTIbundle size;

FIG. 12B is a diagram depicting another example of changing of the TTIbundle size;

FIG. 13A is a diagram (part 1) depicting an example of changing of theRTT;

FIG. 13B is a diagram (part 2) depicting an example of changing of theRTT;

FIG. 13C is a diagram (part 3) depicting one example of the total energyof transmitted packets per unit time;

FIG. 14A is a diagram depicting a first example of a UL grant bitmap inthe transmission power control mode;

FIG. 14B is a diagram depicting the first example of a UL grant bitmapin a TTI bundle size/RTT control mode;

FIG. 15A is a diagram depicting a second example of a UL grant bitmap inthe transmission power control mode;

FIG. 15B is a diagram depicting the second example of a UL grant bitmapin the TTI bundle size/RTT control mode;

FIG. 16A is a diagram (part 1) depicting an example of the transmissionpower control command setting method in the TTI bundle size/RTT controlmode;

FIG. 16B is a diagram (part 2) depicting an example of the transmissionpower control command setting method in the TTI bundle size/RTT controlmode;

FIG. 17 is a sequence diagram depicting one example of operation of thewireless communications system according to a third embodiment;

FIG. 18A is a diagram depicting one example of the eNB according to thethird embodiment;

FIG. 18B is a diagram depicting one example of signal flow in the eNBdepicted in FIG. 18A;

FIG. 19A is a diagram depicting one example of the UE according to thethird embodiment;

FIG. 19B is a diagram depicting one example of signal flow in the UEdepicted in FIG. 19A;

FIG. 20A is a flowchart (part 1) of an example of processing by the eNBaccording to the third embodiment eNB;

FIG. 20B is a flowchart (part 2) of an example of processing by the eNBaccording to the third embodiment eNB;

FIG. 20C is a flowchart (part 3) of an example of processing by the eNBaccording to the third embodiment eNB;

FIG. 21A is a flowchart (part 1) of an example of processing by the UEaccording to the third embodiment UE;

FIG. 21B is a flowchart (part 2) of an example of processing by the UEaccording to the third embodiment UE;

FIG. 21C is a flowchart (part 3) of an example of processing by the UEaccording to the third embodiment UE;

FIG. 22 is a diagram depicting one example of changing a HARQ processcount;

FIG. 23A is a diagram depicting a first example of a UL grant bitmap inthe transmission power control mode;

FIG. 23B is a diagram depicting the first example of a UL grant bitmapin a TTI bundle size/HARQ process count control mode;

FIG. 24A is a diagram depicting a second example of a UL grant bitmap inthe transmission power control mode;

FIG. 24B is a diagram depicting the second example of a UL grant bitmapin the TTI bundle size/HARQ process count control mode;

FIG. 25A is diagram (part 1) depicting an example of the transmissionpower control command setting method in the TTI bundle size/the HARQprocess count control mode;

FIG. 25B is diagram (part 2) depicting an example of the transmissionpower control command setting method in the TTI bundle size/the HARQprocess count control mode;

FIG. 26 is a sequence diagram depicting one example of operation of thewireless communications system according to a fourth embodiment;

FIG. 27A is a diagram depicting one example of the eNB according to thefourth embodiment;

FIG. 27B is a diagram depicting one example of signal flow in the eNBdepicted in FIG. 27A;

FIG. 28A is a diagram depicting one example of the UE according to thefourth embodiment;

FIG. 28B is a diagram depicting one example of signal flow in the UEdepicted in FIG. 28A;

FIG. 29A is a flowchart (part 1) of an example of processing by the eNBaccording to the fourth embodiment;

FIG. 29B is a flowchart (part 2) of an example of processing by the eNBaccording to the fourth embodiment;

FIG. 29C is a flowchart (part 3) of an example of processing by the eNBaccording to the fourth embodiment;

FIG. 30A is a flowchart (part 1) of an example of processing by the UEaccording to the fourth embodiment;

FIG. 30B is a flowchart (part 2) of an example of processing by the UEaccording to the fourth embodiment; and

FIG. 30C is a flowchart (part 3) of an example of processing by the UEaccording to the fourth embodiment.

DESCRIPTION OF THE INVENTION

Embodiments of a wireless communications system, a base station, aterminal, and a process method according to the present invention willbe described in detail with reference to the accompanying drawings.

FIG. 1A is a diagram depicting one example of a wireless communicationssystem according to a first embodiment. FIG. 1B is a diagram depictingone example of signal flow in the wireless communications systemdepicted in FIG. 1A. As depicted in FIGS. 1A and 1B, a wirelesscommunications system 100 according to the first embodiment includes abase station 110 and a terminal 120.

The terminal 120 transmits wireless signals to the base station 110.Further, the terminal 120 may successively transmit the same data to thebase station 110. Consecutive transmission of the same data istransmission of plural wireless signals enabling the same data to bedemodulated at the base station 110. Therefore, provided the wirelesssignals are wireless signals enabling the same data to be demodulated,the wireless signals may be mutually different wireless signals.

The base station 110 includes a transmitting unit 111 and a control unit112. The transmitting unit 111 transmits control information 130 to theterminal 120. The control information 130, for example, is informationindicating radio resources assigned by the base station 110 for thetransmission of wireless signals from the terminal 120 to the basestation 110.

The control unit 112 is capable of switching a first state and a secondstate. In the first state, the control unit 112 stores to apredetermined region 131 of the control information 130 transmitted bythe transmitting unit 111, a value among values instructing thetransmission power of the terminal 120. In the second state, the controlunit 112 stores to the predetermined region 131 of the controlinformation 130, a value among values instructing the transmission countof successive transmissions of the same data by the terminal 120.Further, values stored to the predetermined region 131 by the controlunit 112 in the first state and values stored to the predeterminedregion 131 by the control unit 112 in the second state includeoverlapping values.

The terminal 120 includes a receiving unit 121 and a control unit 122.The receiving unit 121 receives the control information 130 transmittedfrom the base station 110 and outputs the received control information130 to the control unit 122.

The control unit 122 is capable of switching a third state and a fourthstate. The control unit 122, for example, is in the third state when thecontrol unit 112 of the base station 110 is in the first state, and isin the fourth state when the control unit 112 of the base station 110 isin the second state.

In the third state, the control unit 122 adjusts the transmission powerof a wireless signal from the terminal 120 to the base station 110,based on the value of the predetermined region 131 of the controlinformation 130 received from the base station 110 in the first state bythe receiving unit 121. At this time, the control unit 122 does notadjust the transmission count of successive transmissions of the samedata to the base station 110, based on the predetermined region 131.

In the fourth state, the control unit 122 adjusts the transmission countof successive transmissions of the same data by the terminal 120 to thebase station 110, based on the value of the predetermined region 131 ofthe control information 130 received from the base station 110 in thesecond state by the receiving unit 121. At this time, the control unit122 does not adjust the transmission power of the wireless signal to thebase station 110, based on the predetermined region 131.

Thus, according to the first embodiment, the terminal 120 may givenotification of the transmission count of successive transmissions ofthe same data, by using the predetermined region 131 of the controlinformation 130 used in transmission power control of the terminal 120.As a result, the transmission count may be made variable and increasesin the overhead of control information (e.g., the control information130) accompanying notification of the transmission count from the basestation 110 to the terminal 120 may be suppressed.

A first example of a state switching method will be described. Forexample, in the first state, the base station 110 stores to thepredetermined region 131, a value among a value instructing atransmission power and a value instructing switching to the fourthstate. In the second state, the base station 110 stores to thepredetermined region 131, a value among a value instructing atransmission count of successive transmissions of the same data by theterminal 120 and a value instructing switching to the third state. Amongthe first state and the second state, the base station 110 switches tothe state corresponding to the value stored in the predetermined region131. Further, among the third state and the fourth state, the terminal120 switches to the state corresponding to the value of thepredetermined region.

For example, when the base station 110 stores to the predeterminedregion 131, a value instructing switching to the fourth state, theterminal 120 transitions to the fourth state and the base station 110transitions to the second state. Further, when the base station 110stores to the predetermined region 131, a value instructing switching tothe third state, the terminal 120 transitions to the third state and thebase station 110 transitions to the first state.

In this manner, a portion of the values among values that may be storedto the predetermined region 131 may be value instructing stateswitching. As a result, control is enabled such that when the basestation 110 is in the first state, the terminal 120 is in the thirdstate, and when the base station 110 is in the second state, theterminal 120 is in the fourth state.

A second example of a state switching method will be described.Configuration may be such that the terminal 120 transmits informationcorresponding to the transmission power of the terminal 120 to the basestation 110. Further, configuration may be such that among the firststate and the second state, the base station 110 switches to the statethat corresponds to the information received from the terminal 120,corresponding to the transmission power of the terminal 120. In thiscase, among the third state and the fourth state, the terminal 120switches to the state that corresponds to the information transmitted tothe base station 110, corresponding to the transmission power of theterminal 120.

In this manner, information transmitted by the terminal 120 to the basestation 110 and corresponding to the transmission power of the terminal120 may be used in state switching. As a result, control is enabled suchthat when the base station 110 is in the first state, the terminal 120is in the third state, and when the base station 110 is in the secondstate, the terminal 120 is in the fourth state. Further, in thepredetermined region 131, values that may be used in the instructing ofparameters are of a large number, thereby enabling more flexiblecontrol. The information corresponding to the transmission power of theterminal 120, for example, may be information indicating the differenceof the transmission power of the terminal 120 and a maximum transmissionpower of the terminal 120.

Selection of a value based on uplink communication quality will bedescribed. The control unit 112 of the base station 110, for example,may select a value to be stored to the predetermined region 131 based onthe quality of wireless communication from the terminal 120 to the basestation 11. The signal to interference and noise ratio (SINR) at thebase station 110, of a wireless signal from the terminal 120, forexample, may be used as the quality of wireless communication.

A first modification example will be described. In place of thetransmission count of successive transmissions of the same data by theterminal 120, the time until the terminal 120 retransmits data afterhaving transmitted the data to the base station 110 may be controlledusing the predetermined region 131 of the control information 130. As aresult, the time may be made variable and increases in the overhead ofcontrol information (e.g., the control information 130) accompanyingnotification of the time from the base station 110 to the terminal 120may be suppressed.

A second modification example will be described. In place of thetransmission count of successive transmissions of the same data by theterminal 120, a process count of performing with respect to the samedata, a process of successively transmitting the same data by theterminal 120 may be controlled using the predetermined region 131 of thecontrol information 130. As a result, the process count may be madevariable and increases in the overhead of control information (e.g., thecontrol information 130) accompanying notification of the process countfrom the base station 110 to the terminal 120 may be suppressed.

FIG. 2A is a diagram depicting one example of a wireless communicationssystem according to a second embodiment. As depicted in FIG. 2A, awireless communications system 200 according to the second embodiment isa cellular communications system including an eNB 210 and UE 220. TheeNB 210 and the UE 220, for example, may wirelessly communicate underthe Long Term Evolution (LTE) standard. A cell 211 is a region in whichwireless communication with the eNB 210 is possible. The UE 220 islocated in the cell 211 and is user equipment (user terminal) capable ofwirelessly communicating with the eNB 210.

The wireless communications system 100 depicted in FIGS. 1A and 1B, forexample, may be realized by the wireless communications system 200depicted in FIG. 2A. The base station 110 depicted in FIGS. 1A and 1B,for example, may be realized by the eNB 210 depicted in FIG. 2A. Theterminal 120 depicted in FIGS. 1A and 1B, for example, may be realizedby the UE 220 depicted in FIG. 2A.

FIG. 2B is a diagram depicting one example of TTI bundling in uplinkunder LTE. In FIG. 2B, the horizontal axis (subframe) represents time.

An uplink (UL) grant 241 is scheduling information transmitted from theeNB 210 to the UE 220, and is information indicating radio resourcesassigned to uplink communication of the UE 220 by the eNB 210.

The UE 220 performs TTI bundling of transmitting packets representingthe same data, 4 times successively at subframes 231 to 234 (4 TTIs), 4[ms] after a subframe 230 when the UL grant 241 is received. The 4packets transmitted at the subframes 231 to 234, for example, aretransmitted (PUSCH coding) by a Physical Uplink Shared Channel (PUSCH).

The 4 packets transmitted at the subframes 231 to 234 may be mutuallydifferent packets provided the 4 packets enable the same data to bedecoded on the receiving side. For example, the 4 packets transmitted atthe subframes 231 to 234 may be packets respectively having a differingcharacteristic like redundancy version (RV) of HARQ (RV=0, 2, 3, 1). Anexample of the characteristics may be a transmission start position of adata block.

A response signal 242 is a response signal transmitted from the eNB 210to the UE 220 at the subframe 235, 4 [ms] after the subframe 234, inresponse to packets transmitted at the subframes 231 to 234. In theexample depicted in FIG. 2B, the response signal 242 is a NACK(negative-acknowledgement signal) indicating that the data representedby the packets transmitted at the subframes 231 to 234 could not beproperly received (decoded).

The UE 220, having received the response signal 242 (NACK), performs TTIbundling of transmitting packets representing the same data as at thesubframes 231 to 234, 4 times successively at subframes 236 to 239 afteran RTT 243 elapses from the subframe 231. The RTT 243 is the time fromtransmission of the data by the UE 220 until retransmission of the data.In the example depicted in FIG. 2B, the RTT 243 is a round trip time(RTT) of 16 [ms].

FIG. 3 is a diagram depicting one example of a changing of the TTIbundle size. In FIG. 3, the horizontal axis represents time (subframe).At a new transmission 301 depicted in FIG. 3, the UE 220 performs TTIbundling (TTI bundle size=8 TTIs) of successively transmitting to theeNB 210 eight times (8 subframes), packets representing new data thatare the same. At a new transmission 302 subsequent to the newtransmission 301, the UE 220 performs TTI bundling (TTI bundle size=4TTIs) of successively transmitting to the eNB 210 four times (4subframes), packets representing new data that are the same.

At a new transmission 303 subsequent to the new transmission 302, the UE220 performs TTI bundling (TTI bundle size=2 TTIs) of successivelytransmitting to the eNB 210 two times (2 subframes), packetsrepresenting new data that are the same. At a new transmission 304subsequent to the new transmission 303, the UE 220 performs TTI bundling(TTI bundle size=1 TTI) of successively transmitting to the eNB 210 onetime (1 subframe), packets representing new data. The new transmission304 is technically the same as a state where TTI bundling is disabledsince the TTI bundle size is 1.

Under Alt.6.3 of LTE described later, as depicted in FIG. 3, making theTTI bundle size of TTI bundling variable is under consideration. To dothis, the eNB 210 uses a control signal to notify the UE 220 of the TTIbundle size. Here, the eNB 210, for example, uses a TPC command storedin a UL grant to notify the UE 220 of the TTI bundle size. The TPCcommand is a region (e.g., 2 [bit]) of the control signal configured forcontrolling the transmission power of the UE 220. The UE 220 adjusts theTTI bundle size, based on the TPC command stored in the UL grantreceived from the eNB 210.

For example, when TTI bundling between the eNB 210 and the UE 220 hasbeen enabled by the control of an higher layer, the eNB 210 and the UE220 enter a state enabling switching to a transmission power controlmode and the TTI bundle size control mode.

For example, in the transmission power control mode, the UE 220 fixesthe TTI bundle size of the UE 220 to 1 (minimum value). The eNB 210 usesthe TPC command to notify the UE 220 of the transmission power. The UE220 adjusts the transmission power of the UE 220, based on the TPCcommand.

On the other hand, in the TTI bundle size control mode, the UE 220 fixesthe transmission power of the UE 220 to a maximum value. The eNB 210uses the TPC command to notify the UE 220 of the TTI bundle size. The UE220 adjusts the TTI bundle size of the UE 220, based on the TPC command.

In this manner, switching the transmission power control mode of fixingthe TTI bundle size and the TTI bundle size control mode of fixing thetransmission power enables the TPC command for controlling thetransmission power to be further used to control the TTI bundle size. Asa result, increases in the overhead of control information when the TTIbundle size of the UE 220 is made variable may be suppressed. Therefore,the TTI bundle size may be controlled according to wireless channelfluctuations and increases in the overhead of control information may besuppressed.

FIG. 4A is a diagram depicting a first example of a UL grant bitmap inthe transmission power control mode. A table 410 depicted in FIG. 4Aindicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the transmission power control mode.

For example, a TPC command=“00” in the transmission power control modeindicates transition to the TTI bundle size control mode. A TPCcommand=“01” in the transmission power control mode indicates that theTTI bundle size is to be maintained at 1 and a transmission powerincrement is to be −1 [dB].

A TPC command=“10” in the transmission power control mode indicates thatthe TTI bundle size is to be maintained at 1 and the transmission powerincrement is to be 0 [dB] (no change). A TPC command=“11” in thetransmission power control mode indicates that the TTI bundle size is tobe maintained at 1 and the transmission power increment is to be 1 [dB].

FIG. 4B is a diagram depicting the first example of a UL grant bitmap inthe TTI bundle size control mode. A table 420 depicted in FIG. 4Bindicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the TTI bundle size control mode.

For example, a TPC command=“00” in the TTI bundle size control modeindicates that the TTI bundle size is to be 1 and indicates transitionto the transmission power control mode. A TPC command=“01” in the TTIbundle size control mode indicates that the TTI bundle size is to be 2.

A TPC command=“10” in the TTI bundle size control mode indicates thatthe TTI bundle size is to be 4. A TPC command=“11” in the TTI bundlesize control mode indicates that the TTI bundle size is to be 8.

FIG. 5A is a diagram depicting a second example of a UL grant bitmap inthe transmission power control mode. A table 510 depicted in FIG. 5Aindicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the transmission power control mode.

For example, a TPC command=“00” in the transmission power control modeindicates that the TTI bundle size is to be maintained at 1 and thetransmission power increment is to be −1 [dB]. A TPC command=“01” in thetransmission power control mode indicates that the TTI bundle size is tobe maintained at 1 and the transmission power increment is to be 0 [dB].

A TPC command=“10” in the transmission power control mode indicates thatthe TTI bundle size is to be maintained at 1 and the transmission powerincrement is to be 1 [dB]. A TPC command=“11” in the transmission powercontrol mode indicates that the TTI bundle size is to be maintained at 1and the transmission power increment is to be 3 [dB].

In this manner, transition to the TTI bundle size control mode need notbe explicitly notified by a TPC command. In this case, the eNB 210 andthe UE 220, for example, may determine transition to the TTI bundle sizecontrol mode, based on power headroom reporting (PHR). As a result,since the type of transmission power increment that can be instructed bya TPC command increases, more flexible control of the transmission powerof the UE 220 becomes possible.

PHR is information indicating the state of the transmission power of theUE 220 and, for example, indicates the difference of the maximumtransmission power of the UE 220 and a transmission power desired by theeNB 210. Further, the PHR is transmitted, as a MAC control element,accompanying an uplink data signal from the UE 220 to the eNB 210.

The PHR, for example, is a value (predetermined value) of 0 or less whenthe transmission power of the UE 220 reaches the maximum value.Therefore, the eNB 210 transitions to the TTI bundle size control mode,when the PHR received from the UE 220 is 0 or less. Further, the UE 220transitions to the TTI bundle size control mode, when the PHRtransmitted to the eNB 210 is 0 or less. As a result, when thetransmission power of the UE 220 reaches the maximum value in thetransmission power control mode, the TTI bundle size control mode may betransitioned to.

FIG. 5B is a diagram depicting the second example of a UL grant bitmapin the TTI bundle size control mode. A table 520 depicted in FIG. 5Bindicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the TTI bundle size control mode, i.e.,when the transmission power of the UE 220 reaches the maximum value (ata time of maximum transmission power). The table 520 depicted in FIG.5B, for example, may be the same as the table 420 depicted in FIG. 4B.Hereinafter, in the second embodiment, a case where the UL grant bitmap(second example) depicted in FIGS. 5A and 5B is used will be described.

FIG. 6A is a diagram depicting one example of a transmission powercontrol command setting method in the transmission power control mode. Atable 610 depicted in FIG. 6A indicates a correspondence relation of aTPC command selected by the eNB 210 and a condition related to adifference Diff from a targeted value for the measured value ofreception SINR, in the transmission power control mode. The differenceDiff is a value obtained by subtracting a predetermined target valuefrom the measured value of reception SINR, which is the quality ofreception from the UE 220, at the eNB 210.

For example, when Diff>0.5 [dB], the eNB 210 selects the TPCcommand=“00” indicating the transmission power increment=−1 [dB]. When0.5 [dB]≥Diff>−0.5 [dB], the eNB 210 selects the TPC command=“01”indicating the transmission power increment=0 [dB]. When −0.5[dB]≥Diff>−1.5 dB [dB], the eNB 210 selects the TPC command=“10”indicating the transmission power increment=1 [dB]. When −1.5 [dB]≥Diff,the eNB 210 selects the TPC command=“11” indicating the transmissionpower increment=3 [dB].

FIGS. 6B and 6C are diagrams depicting examples of the transmissionpower control command setting method in the TTI bundle size controlmode. A table 620 depicted in FIG. 6B indicates a correspondencerelation of a TTI bundle size adjustment amount selected by the eNB 210and a condition related to the difference Diff from a targeted value forthe measured value of reception SINR, in the TTI bundle size controlmode.

For example, when Diff>7.5 [dB], the eNB 210 selects ⅛ times as the TTIbundle size adjustment amount. When 7.5 [dB]≥≥Diff>4.5 [dB], the eNB 210selects ¼ times as the TTI bundle size adjustment amount. When 4.5[dB]≥Diff>1.5 [dB], the eNB 210 selects ½ times as the TTI bundle sizeadjustment amount.

When 1.5 [dB]≥Diff>−1.5 [dB], the eNB 210 selects 1 time (no change) asthe TTI bundle size adjustment amount. When −1.5 [dB]≥Diff>−4.5 [dB],the eNB 210 selects 2 times as the TTI bundle size adjustment amount.When −4.5 [dB]≥Diff>−7.5 [dB], the eNB 210 selects 4 times as the TTIbundle size adjustment amount. When −7.5 [dB]≥Diff, the eNB 210 selects8 times as the TTI bundle size adjustment amount.

A table 630 depicted in FIG. 6C indicates a correspondence relation ofan adjustment result of the TTI bundle size based on the selected TTIbundle size adjustment amount and a TPC command selected by the eNB 210,in the TTI bundle size control mode. For example, when the adjustmentresult≤1, the eNB 210 selects the TPC command=“00” indicating the TTIbundle size=1 and transition to the transmission power control mode.

When the adjustment result=2, the eNB 210 selects the TPC command=“01”indicating the TTI bundle size=2. When the adjustment result=4, the eNB210 selects the TPC command=“10” indicating the TTI bundle size=4. Whenthe adjustment result≥8, the eNB 210 selects the TPC command=“11”indicating the TTI bundle size=8.

FIG. 7 is a sequence diagram depicting one example of operation of thewireless communications system according to the second embodiment. Inthe wireless communications system 200 according to the secondembodiment, for example, the following steps are performed.

The eNB 210 enables TTI bundling with the UE 220 (step S701). The eNB210 transmits to the UE 220, an higher layer control signal (TTIbundling=TRUE) instructing TTI bundling to be enabled (step S702).

The UE 220 enables TTI bundling with the eNB 210 (step S703). In theexample depicted in FIG. 7, the eNB 210 and the UE 220, which haveenable TTI bundling, are assumed to be in the TTI bundle size controlmode as an initial mode.

The UE 220 transmits a sounding reference signal (RS) to the eNB 210(step S704). The eNB 210 measures the reception quality based on thesounding RS transmitted at step S704. The reception quality, forexample, is the reception SINR. In the example depicted in FIG. 7, theeNB 210 is assumed to set the TTI bundle size of the UE 220 to bechanged to 1 TTI, based on the reception quality measured at step S705.

The eNB 210 transmits to the UE 220, a UL grant based on the receptionquality measured at step S705 (step S706). The UL grant at step S706includes the TPC command=“00”. In other words, the UL grant at step S706includes a TPC command instructing the TTI bundle size to be configuredto 1 TTI and transition to the transmission power control mode (forexample, refer to FIG. 5B).

The UE 220 adjusts the TTI bundle size of the UE 220 to 1 TTI, based onthe TPC command included in the UL grant transmitted at step S706 (stepS707). The UE 220 transmits a PUSCH and PHR by a radio resourceinstructed by the UL grant transmitted at step S706 (step S708).Transmission of the PUSCH at step S708 is performed by TTI bundling oftransmitting the PUSCH one time.

Consequent to step S706, the eNB 210 and the UE 220 transition to thetransmission power control mode.

The UE 220 transmits a sounding RS to the eNB 210 (step S709). The eNB210 measures the reception quality based on the sounding RS transmittedat step S709 (step S710). In the example depicted in FIG. 7, the eNB 210sets the transmission power of the UE 220 to be increased 3 [dB] basedon the reception quality measured at step S710.

The eNB 210 transmits to the UE 220, a UL grant based on the receptionquality measured at step S710 (step S711). The UL grant at step S711includes the TPC command=“11”. In other words, the UL grant at step S711includes a TPC command instructing the transmission power to beincreased 3 [dB] (for example, refer to FIG. 5A).

The UE 220 performs adjustment such that the transmission powerincreases 3 [dB], based on the TPC command included in the UL granttransmitted at step S711 (step S712). Consequent to step S712, thetransmission power of the UE 220 is assumed to reach the maximumtransmission power. Therefore, the PHR of the UE 220 becomes 0 or less.

The UE 220 transmits a PUSCH and PHR by a radio resource instructed bythe UL grant transmitted at step S711 (step S713). Transmission of thePUSCH at step S713 is performed by TTI bundling of transmitting thePUSCH one time.

Consequent to the PHR of the UE 220 becoming 0 [dB] or less, the eNB 210and the UE 220 transition to the TTI bundle size control mode.

The UE 220 transmits a sounding RS to the eNB 210 (step S714). The eNB210 measures the reception quality based on the sounding RS transmittedat step S714 (step S715). In the example depicted in FIG. 7, the eNB 210is assumed to set the TTI bundle size of the UE 220 to be changed to 2TTI, based on the reception quality measured at step S714.

The eNB 210 transmits to the UE 220, a UL grant based on the receptionquality measured at step S715 (step S716). The UL grant at step S716includes the TPC command=“01”. In other words, the UL grant at step S716includes a TPC command instructing the TTI bundle size to be configuredto 2 TTIs (for example, refer to FIG. 5B).

The UE 220 adjusts the TTI bundle size to 2 TTIs, based on the TPCcommand included in the UL grant transmitted at step S716 (step S717).The UE 220 transmits a PUSCH and PHR by a radio resource instructed bythe UL grant transmitted at step S716 (step S718). Transmission of thePUSCH at step S718 is performed by TTI bundling of transmittingsuccessively 2 times, a PUSCH representing the same data.

Transmission of the sounding RS at steps S704, S709, and S714, forexample, may be transmission of a periodic sounding RS by the UE 220.

FIG. 8A is a diagram depicting one example of the eNB according to thesecond embodiment. FIG. 8B is a diagram depicting one example of signalflow in the eNB depicted in FIG. 8A. As depicted in FIGS. 8A and 8B, theeNB 210 according to the second embodiment includes a reception antenna801, a reception RF unit 802, the PUSCH demodulating unit 803, and areception SINR estimating unit 804.

The eNB 210 further includes a transmission power control commandgenerating unit 805, a TTI bundling command generating unit 806, a PUSCHscheduler 807, a UL grant generating unit 808, a long-interval receptionquality determining unit 809, and a PDSCH generating unit 810. The eNB210 further includes a physical channel multiplexing unit 811, atransmission RF unit 812, a transmission antenna 813, and a modeswitching control unit 814.

The reception antenna 801 receives an uplink signal (uplink receptionsignal) wirelessly transmitted from the UE 220 and outputs the receivedsignal to the reception RF unit 802. The reception RF unit 802 performsreception RF processing of the signal output from the reception antenna801. In the reception RF processing, for example, frequency conversionfrom a radio frequency (RF) bandwidth to a baseband bandwidth isincluded. The reception RF unit 802 outputs a signal obtained by thereception RF processing to the PUSCH demodulating unit 803 and thereception SINR estimating unit 804.

The PUSCH demodulating unit 803 demodulates the PUSCH and PHR includedin the signal output from the reception RF unit 802. The PUSCHdemodulating unit 803 outputs the demodulated PHR to the mode switchingcontrol unit 814.

The reception SINR estimating unit 804 estimates reception SINR based ona reference signal (e.g., a sounding RS from the UE 220) included in thesignal output from the reception RF unit 802. The reception SINRestimating unit 804 outputs the estimated reception SINR to thetransmission power control command generating unit 805 and the TTIbundling command generating unit 806, the long-interval receptionquality determining unit 809 and the mode switching control unit 814.

The transmission power control command generating unit 805 generates atransmission power control command for the UE 220 based on the receptionSINR output from the reception SINR estimating unit 804, in thetransmission power control mode, based on a switching result from themode switching control unit 814. The transmission power control commandis information instructing a transmission power. The transmission powercontrol command generating unit 805 outputs the generated transmissionpower control command to the UL grant generating unit 808.

The TTI bundling command generating unit 806 generates a TTI bundlingcommand for the UE 220 based on the reception SINR output from thereception SINR estimating unit 804, in the TTI bundle size control mode,based on the switching result from the mode switching control unit 814.The TTI bundling command is information instructing a TTI bundle size.The TTI bundling command generating unit 806 outputs the generated TTIbundling command to the PUSCH scheduler 807 and the UL grant generatingunit 808.

The PUSCH scheduler 807 performs scheduling of the PUSCH for the UE 220,based on the TTI bundling command output from the TTI bundling commandgenerating unit 806. For example, the PUSCH scheduler 807 performsscheduling of assigning to the UE 220, successive subframescorresponding to the TTI bundle size indicated by the TTI bundlingcommand. The PUSCH scheduler 807 outputs a scheduling result for thePUSCH to the UL grant generating unit 808.

The UL grant generating unit 808 generates a UL grant indicating thePUSCH scheduling result output from the PUSCH scheduler 807. The ULgrant is downlink control information transmitted to the UE 220 as aPhysical Downlink Control Channel (PDCCH).

The UL grant generating unit 808 stores to the UL grant as a TPCcommand, the TTI bundling command output from the TTI bundling commandgenerating unit 806 or the transmission power control command outputfrom the transmission power control command generating unit 805. The ULgrant generating unit 808 transmits the UL grant storing therein the TPCcommand to the physical channel multiplexing unit 811.

The long-interval reception quality determining unit 809 calculates atemporal average of the reception SINR output from the reception SINRestimating unit 804, compares the calculated result with a threshold andthereby, determines the long-interval reception quality of the UE 220.The temporal average, for example, may use a movement average. Thelong-interval reception quality determining unit 809 outputs to thePDSCH generating unit 810 and the mode switching control unit 814, anhigher layer control signal indicating enabling/disabling of TTIbundling, based on the determined long-interval reception quality. Thehigher layer control signal, for example, is a control signal of theradio link control (RLC) layer.

The PDSCH generating unit 810 generates a Physical Downlink SharedChannel (PDSCH) that includes the higher layer control signal outputfrom the long-interval reception quality determining unit 809. The PDSCHgenerating unit 810 outputs the generated PDSCH to the physical channelmultiplexing unit 811.

The physical channel multiplexing unit 811 multiplexes the UL grant(PDCCH) output from the UL grant generating unit 808 and the PDSCHoutput from the PDSCH generating unit 810. The physical channelmultiplexing unit 811 outputs the signal obtained by the multiplexing(multiplexed signal) to the transmission RF unit 812.

The transmission RF unit 812 performs transmission RF processing of thesignal output from the physical channel multiplexing unit 811. In thetransmission RF processing, for example, frequency conversion from thebaseband bandwidth to the RF bandwidth is included. The transmission RFunit 812 outputs to the transmission antenna 813, the signal subject tothe transmission RF processing. The transmission antenna 813 wirelesslytransmits to the UE 220, the signal (downlink transmission signal)output from the transmission RF unit 812.

The mode switching control unit 814 begins switching control of the TTIbundle size control mode and the transmission power control mode, whenTTI bundling between the eNB 210 and the UE 220 is enabled, based on thehigher layer control signal output from the long-interval receptionquality determining unit 809. In particular, the mode switching controlunit 814 performs switching of the modes, based on the reception SINRoutput from the reception SINR estimating unit 804, or the PHR outputfrom the PUSCH demodulating unit 803. The mode switching control unit814 outputs a switching result to the transmission power control commandgenerating unit 805 and the TTI bundling command generating unit 806.

The transmitting unit 111 depicted in FIGS. 1A and 1B, for example, maybe realized by the physical channel multiplexing unit 811, thetransmission RF unit 812, and the transmission antenna 813. The controlunit 112 depicted in FIGS. 1A and 1B, for example, may be realized bythe transmission power control command generating unit 805, the TTIbundling command generating unit 806, the UL grant generating unit 808,the long-interval reception quality determining unit 809, and the modeswitching control unit 814.

FIG. 8C is a diagram depicting one example of hardware configuration ofthe eNB. The eNB 210 depicted in FIGS. 8A and 8B, for example, may berealized by a communications apparatus 830 depicted in FIG. 8C. Thecommunications apparatus 830 includes a CPU 831, memory 832, a wirelesscommunications interface 833, and a wired communications interface 834.The CPU 831, the memory 832, the wireless communications interface 833,and the wired communications interface 834 are connected by a bus 839.

The CPU (central processing unit) 831 governs overall control of thecommunications apparatus 830. The memory 832, for example, includes mainmemory and auxiliary memory. The main memory, for example, is randomaccess memory (RAM). The main memory is used as a work area of the CPU831. The auxiliary memory, for example, is non-volatile memory such as amagnetic disk, an optical disk, and flash memory. The auxiliary memorystores various types of programs operating the communications apparatus830. a program stored by the auxiliary memory is loaded onto the mainmemory and is executed by the CPU 831.

The wireless communications interface 833 is a communications interfacethat performs wireless communication with an external device (e.g., theUE 220) of the communications apparatus 830. The wireless communicationsinterface 833 is controlled by the CPU 831.

The wired communications interface 834 is a communications interfacethat performs wired communication with an external device (e.g., upperlevel device) of the communications apparatus 830. The wiredcommunications interface 834 is controlled by the CPU 831.

The reception antenna 801, the reception RF unit 802, the transmissionRF unit 812, and the transmission antenna 813 depicted in FIGS. 8A and8B, for example, may be realized by the wireless communicationsinterface 833. The PUSCH demodulating unit 803, the reception SINRestimating unit 804, the transmission power control command generatingunit 805, the TTI bundling command generating unit 806, and the PUSCHscheduler 807 depicted in FIGS. 8A and 8B may be realized, for example,by the CPU 831. The UL grant generating unit 808, the long-intervalreception quality determining unit 809, the PDSCH generating unit 810,the physical channel multiplexing unit 811, the transmission RF unit812, the transmission antenna 813, and the mode switching control unit814 depicted in FIGS. 8A and 8B, for example, may be realized by the CPU831.

FIG. 9A is a diagram depicting one example of the UE according to thesecond embodiment. FIG. 9B is a diagram depicting one example of signalflow in the UE depicted in FIG. 9A. As depicted in FIGS. 9A and 9B, theUE 220 according to the second embodiment includes a reception antenna901, a reception RF unit 902, a PDSCH demodulating unit 903, a PDCCHdemodulating unit 904, a mode switching control unit 905, and atransmission power calculating unit 906. The UE 220 further includes aTTI bundling control unit 907, a PUSCH scheduler 908, a SRS generatingunit 909, a physical channel multiplexing unit 910, a transmission powercontrol unit 911, a transmission RF unit 912, and a transmission antenna913.

The reception antenna 901 receives a downlink signal (downlink receptionsignal) wirelessly transmitted from the eNB 210 and outputs the receivedsignal to the reception RF unit 902. The reception RF unit 902 performsreception RF processing of the signal output from the reception antenna901. In the reception RF processing, for example, frequency conversionfrom the RF bandwidth to the baseband bandwidth is included. Thereception RF unit 902 outputs a signal obtained by the reception RFprocessing to the PDSCH demodulating unit 903 and the PDCCH demodulatingunit 904.

The PDSCH demodulating unit 903 demodulates a PDSCH included in thesignal output from the reception RF unit 902. The PDSCH demodulatingunit 903 outputs to the mode switching control unit 905, an higher layercontrol signal included in the demodulated PDSCH.

The PDCCH demodulating unit 904 demodulates a PDCCH included in thesignal output from the reception RF unit 902. The PDCCH demodulatingunit 904 outputs the demodulated PDCCH (UL grant) to the mode switchingcontrol unit 905, the transmission power calculating unit 906, the TTIbundling control unit 907, and the PUSCH scheduler 908.

The mode switching control unit 905 begins switching control of the TTIbundle size control mode and the transmission power control mode, whenTTI bundling with the eNB 210 is enabled, based on the higher layercontrol signal output from the PDSCH demodulating unit 903. Inparticular, the mode switching control unit 905 performs switching ofthe modes, based on the TPC command stored in a TPC region of the ULgrant (PDCCH) output from the PDCCH demodulating unit 904.

The mode switching control unit 905 switches to the TTI bundle sizecontrol mode from the next transmission, when the PHR output from thetransmission power calculating unit 906 is 0 or less. The mode switchingcontrol unit 905 outputs a mode switching result to the transmissionpower calculating unit 906 and the TTI bundling control unit 907.

The transmission power calculating unit 906 calculates the transmissionpower of the UE 220 for a case where the transmission power of the UE220 is adjusted based on the UL grant output from the PDCCH demodulatingunit 904, in the transmission power control mode, based on the switchingresult output from the mode switching control unit 905. The transmissionpower calculating unit 906 notifies the transmission power control unit911 of the calculated transmission power. The transmission powercalculating unit 906 outputs to the mode switching control unit 905 andthe PUSCH scheduler 908, PHR based on the maximum transmission power ofthe UE 220 and the calculated transmission power.

The TTI bundling control unit 907 obtains a TPC command stored in the ULgrant output from the PDCCH demodulating unit 904, in the TTI bundlesize control mode, based on the switching result output from the modeswitching control unit 905. The TTI bundling control unit 907 sets theTTI bundle size based on the obtained TPC command. The TTI bundlingcontrol unit 907 notifies the PUSCH scheduler 908 of the set TTI bundlesize.

The PUSCH scheduler 908 performs scheduling of a PUSCH from the UE 220to the eNB 210, based on the UL grant output from the PDCCH demodulatingunit 904. The PUSCH scheduler 908 performs scheduling of the PUSCH suchthat successive transmission by the TTI bundle size output from the TTIbundling control unit 907 is performed. The PUSCH scheduler 908 outputsto the physical channel multiplexing unit 910, the PUSCH based on ascheduling result. The PUSCH scheduler 908 performs scheduling of thePHR output from the transmission power calculating unit 906, and outputsthe PHR to the physical channel multiplexing unit 910, based on thescheduling result.

The SRS generating unit 909 generates and outputs to the physicalchannel multiplexing unit 910, a periodic sounding RS (SoundingReference Signal).

The physical channel multiplexing unit 910 multiplexes the sounding RSoutput from the SRS generating unit 909 and the PHR and PUSCH outputfrom the PUSCH scheduler 908. The physical channel multiplexing unit 910outputs a signal obtained by the multiplexing (multiplexed signal) tothe transmission power control unit 911.

The transmission power control unit 911 controls the transmission powerof a signal output from the physical channel multiplexing unit 910 tobecome the transmission power notified by the transmission powercalculating unit 906. The transmission power control unit 911 outputsthe transmission power controlled signal to the transmission RF unit912.

The transmission RF unit 912 performs transmission RF processing of thesignal output from the transmission power control unit 911. Intransmission RF processing, for example, frequency conversion from thebaseband bandwidth to the RF bandwidth is included. The transmission RFunit 912 outputs to the transmission antenna 913, the signal subject tothe transmission RF processing. The transmission antenna 913 wirelesslytransmits to the eNB 210, the signal (uplink transmission signal) outputfrom the transmission RF unit 912.

The receiving unit 121 depicted in FIGS. 1A and 1B, for example, may berealized by the reception antenna 901, the reception RF unit 902, andthe PDCCH demodulating unit 904. The control unit 122 depicted in FIGS.1A and 1B, for example, may be realized by the mode switching controlunit 905, the transmission power calculating unit 906, and the TTIbundling control unit 907.

FIG. 9C is a diagram depicting one example of hardware configuration ofthe UE. The UE 220 depicted in FIGS. 9A and 9B, for example, may berealized by a communications apparatus 930 depicted in FIG. 9C. Thecommunications apparatus 930 includes a CPU 931, memory 932, a userinterface 933, and a wireless communications interface 934. The CPU 931,the memory 932, the user interface 933, and the wireless communicationsinterface 934 are connected by a bus 939.

The CPU 931 governs overall control of the communications apparatus 930.The memory 932, for example, includes main memory and auxiliary memory.The main memory, for example, is RAM. The main memory is used as a workarea of the CPU 931. The auxiliary memory, for example, is non-volatilememory such as a magnetic disk, flash memory, etc. The auxiliary memorystores various types of programs operating the communications apparatus930. A program stored in the auxiliary memory is loaded onto the mainmemory and executed by the CPU 931.

The user interface 933, for example, includes an input device thatreceives operation input from a user, an output device that outputsinformation to the user, etc. The input device, for example, may berealized by keys (e.g., keyboard) or remote controller. The outputdevice, for example, may be realized by a display or a speaker. Further,the input device and the output device may be realized by a touch panelor the like. The user interface 933 is controlled by the CPU 931.

The wireless communications interface 934 is a communications interfacethat performs wireless communication with an external device (e.g., theeNB 210) of the communications apparatus 930. The wirelesscommunications interface 934 is controlled by the CPU 931.

The reception antenna 901, the reception RF unit 902, the transmissionRF unit 912, and the transmission antenna 913 depicted in FIGS. 9A and9B, for example, may be realized by the wireless communicationsinterface 934. The PDSCH demodulating unit 903, the PDCCH demodulatingunit 904, the mode switching control unit 905, the transmission powercalculating unit 906, and the TTI bundling control unit 907 depicted inFIGS. 9A and 9B, for example, may be realized by the CPU 931. The PUSCHscheduler 908, the SRS generating unit 909, the physical channelmultiplexing unit 910, and the transmission power control unit 911depicted in FIGS. 9A and 9B, for example, may be realized by the CPU931.

FIGS. 10A, 10B, and 10C are flowcharts of an example of processing bythe eNB according to the second embodiment. The eNB 210 according to thesecond embodiment, for example, executes the steps depicted in FIGS. 10Ato 10C. The eNB 210 measures the long-interval reception quality fromthe UE 220 (step S1001). The long-interval reception quality, forexample, is a temporal average of the reception SINR.

The eNB 210 determines based on a measurement result at step S1001, ifthe long-interval reception quality from the UE 220 is a default valueor less (step S1002). If the reception quality is not the default valueor less (step S1002: NO), the eNB 210 transmits to the UE 220, an higherlayer control signal indicating that TTI bundling is to be disabled(FALSE) (step S1003).

The eNB 210 measures the instantaneous reception quality from the UE 220(step S1004). The instantaneous reception quality, for example, is aninstantaneous value of the reception SINR. The eNB 210 determineswhether the reception SINR measured at step S1004 is higher than apredetermined target value (step S1005). If the reception SINR is higherthan the predetermined target value (step S1005: YES), the eNB 210configures the TPC command to be “00” (step S1006), and transitions tostep S1012.

At step S1005, if the reception SINR is not higher than thepredetermined target value (step S1005: NO), the eNB 210 determineswhether the reception SINR measured at step S1004 is on the same orderas the predetermined target value (step S1007). If the reception SINR ison the same order as the predetermined target value (step S1007: YES),the eNB 210 configures the TPC command to be “01” (step S1008), andtransitions to step S1012.

At step S1007, if the reception SINR is not on the same order as thepredetermined target value (step S1007: NO), the eNB 210 determineswhether the reception SINR measured at step S1004 is about 1 [dB] lessthan the predetermined target value (step S1009). If the reception SINRis about 1 [dB] less than the predetermined target value (step S1009:YES), the eNB 210 configures the TPC command to be “10” (step S1010),and transitions to step S1012.

At step S1009, if the reception SINR is not about 1 [dB] less than thepredetermined target value (step S1009: NO), i.e., the difference of thereception SINR with respect to the predetermined target value is greaterthan 1 [dB], the eNB 210 transitions to step S1011. In particular, theeNB 210 configures the TPC command to be “11” (step S1011), andtransitions to step S1012.

The eNB 210 transmits to the UE 220, the UL grant storing the TPCcommand configured at the steps S1005 to S1011 (step S1012). The eNB 210receives a PUSCH from the UE 220, by a radio resource instructed by theUL grant transmitted at step S1012 (step S1013).

The eNB 210 determines whether the determination timing for thelong-interval reception quality has arrived (step S1014). Thedetermination timing for the reception quality, for example, is aperiodic timing. If the determination timing has not arrived (stepS1014: NO), the eNB 210 returns to step S1004. If the determinationtiming has arrived (step S1014: YES), the eNB 210 returns to step S1001.

At step S1002, if the long-interval reception quality is the defaultvalue or less (step S1002: YES), the eNB 210 enables TTI bundling withthe UE 220 (step S1015). The eNB 210 transmits to the UE 220, an higherlayer control signal indicating that TTI bundling is to be enabled(TRUE) (step S1016). The eNB 210 measures the instantaneous receptionquality from the UE 220 (step S1017).

The eNB 210 determines whether the current mode is the TTI bundle sizecontrol mode (step S1018). If the current mode is the transmission powercontrol mode and not the TTI bundle size control mode (step S1018: NO),the eNB 210 transitions to step S1019. Steps S1019 to S1027 areidentical to steps S1005 to S1013.

At step S1027, the eNB 210 determines if the PHR from the UE 220 is 0[dB] or less (step S1028). If the PHR is not 0 [dB] or less (step S1028:NO), the eNB 210 maintains the transmission power control mode (stepS1029), and transitions to step S1031. If the PHR is 0 [dB] or less(step S1028: YES), the eNB 210 transitions to the TTI bundle sizecontrol mode (step S1030), and transitions to step S1031.

The eNB 210 determines whether the determination timing for thelong-interval reception quality has arrived (step S1031). If thedetermination timing has not arrived (step S1031: NO), the eNB 210returns to step S1017. If the determination timing has arrived (stepS1031: YES), the eNB 210 returns to step S1001.

At step S1018, if the current mode is the TTI bundle size control mode(step S1018: YES), the eNB 210 transitions to step S1032. In otherwords, the eNB 210 sets the TTI bundle size adjustment amount of the UE220, based on the difference of the reception SINR measured at stepS1017 and the predetermined target value (step S1032).

The eNB 210 determines if the TTI bundle size of the UE 220 afteradjustment based on the adjustment amount set at step S1032 is 1 or less(step S1033). If the TTI bundle size after adjustment is 1 or less (stepS1033: YES), the eNB 210 configures the TPC command to be “00” (stepS1034), and transitions to step S1040.

At step S1033, if the TTI bundle size after adjustment is not 1 or less(step S1033: NO), the eNB 210 determines whether the TTI bundle sizeafter adjustment is 2 (step S1035). If the TTI bundle size afteradjustment is 2 (step S1035: YES), the eNB 210 configures the TPCcommand to be “01” (step S1036), and transitions to step S1040.

At step S1035, if the TTI bundle size after adjustment is not 2 (stepS1035: NO), the eNB 210 determines whether the TTI bundle size afteradjustment is 4 (step S1037). If the TTI bundle size after adjustment is4 (step S1037: YES), the eNB 210 configures the TPC command to be “10”(step S1038), and transitions to step S1040.

At step S1037, if the TTI bundle size after adjustment is not 4 (stepS1037: NO), the eNB 210 configures the TPC command to be “11” (stepS1039), and transitions to step S1040.

The eNB 210 transmits to the UE 220, the UL grant storing the TPCcommand configured by steps S1033 to S1039 (step S1040). The eNB 210receives a PUSCH from the UE 220, by a radio resource instructed by theUL grant transmitted at step S1040 (step S1041). The eNB 210 determineswhether the TPC command configured by steps S1033 to S1039 is “00” (stepS1042).

At step S1042, if the TPC command is not “00” (step S1042: NO), the eNB210 maintains the TTI bundle size control mode (step S1043), andtransitions to step S1031. If the TPC command is “00” (step S1042: YES),the eNB 210 transitions to the transmission power control mode (stepS1044), and transitions to step S1031.

FIGS. 11A, 11B, and 11C are flowcharts of an example of processing bythe UE according to the second embodiment. The UE 220 according to thesecond embodiment, for example, executes the steps depicted in FIGS. 11Ato 11C. The UE 220 determines whether TTI bundling with the eNB 210 isenabled (TRUE) (step S1101). The determination at step S1101 may beperformed based on an higher layer control signal received from the eNB210.

At step S1101, if TTI bundling is not enabled (step S1101: NO), the UE220 transmits a sounding RS to the eNB 210 (step S1102). The UE 220receives a UL grant from the eNB 210 (step S1103).

The UE 220 determines whether the TPC command stored in the UL grantreceived at step S1103 is “00” (step S1104). If the TPC command is “00”(step S1104: YES), the UE 220 determines that the transmission powerincrement is −1 [dB] (step S1105), and transitions to step S1111.

At step S1104, if the TPC command is not “00” (step S1104: NO), the UE220 determines whether the TPC command is “01” (step S1106). If the TPCcommand is “01” (step S1106: YES), the UE 220 determines that thetransmission power increment is 0 [dB] (step S1107), and transitions tostep S1111.

At step S1106, if the TPC command is not “01” (step S1106: NO), the UE220 determines whether the TPC command is “10” (step S1108). If the TPCcommand is “10” (step S1108: YES), the UE 220 determines that thetransmission power increment is 1 [dB] (step S1109), and transitions tostep S1111.

At step S1108, if the TPC command is not “10” (step S1108: NO), the UE220 determines whether the transmission power increment is 3 [dB] (stepS1110), and transitions to step S1111.

The UE 220 adjusts the transmission power of the UE 220 based on thetransmission power increment determined at steps S1104 to S1110 (stepS1111). The UE 220 transmits a PUSCH and PHR to the eNB 210, by thetransmission power adjusted at step S1111, at a radio resource indicatedby the UL grant received at step S1103 (step S1112).

The UE 220 determines whether a reception timing for an higher layercontrol signal has arrived (step S1113). The reception timing for anhigher layer control signal, for example, is periodic timing. If thereception timing for an higher layer control signal has not arrived(step S1113: NO), the UE 220 returns to step S1103. If the receptiontiming for an higher layer control signal has arrived (step S1113: YES),the UE 220 returns to step S1101.

At step S1101, if TTI bundling is enabled (step S1101: YES), the UE 220internally enables TTI bundling (step S1114). The UE 220 transmits asounding RS to the eNB 210 (step S1115). The UE 220 receives a UL grantfrom the eNB 210 (step S1116).

The UE 220 determines whether the current mode is the TTI bundle sizecontrol mode (step S1117). If the current mode is the transmission powercontrol mode and not the TTI bundle size control mode (step S1117: NO),the UE 220 transitions to step S1118. Steps S1118 to S1125 are identicalto steps S1104 to S1111.

After step S1125, the UE 220 determines if the PHR at the UE 220 is 0[dB] or less (step S1126). If the PHR is not 0 [dB] or less (step S1126:NO), the UE 220 maintains the transmission power control mode (stepS1127), and transitions to step S1129. If the PHR is 0 [dB] or less(step S1126: YES), the UE 220 transitions to the TTI bundle size controlmode (step S1128), and transitions to step S1129.

The UE 220 transmits a PUSCH and PHR to the eNB 210, by the transmissionpower adjusted at step S1125, at a radio resource indicated by the ULgrant received at step S1116 (step S1129). The UE 220 determines whetherthe reception timing for an higher layer control signal has arrived(step S1130). If the reception timing for an higher layer control signalhas not arrived (step S1130: NO), the UE 220 returns to step S1116. Ifthe reception timing for an higher layer control signal has arrived(step S1130: YES), the UE 220 returns to step S1101.

At step S1117, if the current mode is the TTI bundle size control mode(step S1117: YES), the UE 220 determines whether the TPC command storedin the UL grant received at step S1116 is “00” (step S1131). If the TPCcommand is “00” (step S1131: YES), the UE 220 determines that the TTIbundle size is 1 (step S1132), and transitions to step S1138.

At step S1131, if the TPC command is not “00” (step S1131: NO), the UE220 determines whether the TPC command is “01” (step S1133). If the TPCcommand is “01” (step S1133: YES), the UE 220 determines that the TTIbundle size is 2 (step S1134), and transitions to step S1138.

At step S1133, if the TPC command is not “01” (step S1133: NO), the UE220 determines whether the TPC command is “10” (step S1135). If the TPCcommand is “10” (step S1135: YES), the UE 220 determines that the TTIbundle size is 4 (step S1136), and transitions to step S1138.

At step S1135, if the TPC command is not “10” (step S1135: NO), the UE220 determines that the TTI bundle size is 8 (step S1137), andtransitions to step S1138.

The UE 220 adjusts the TTI bundle size by the TTI bundle size determinedat steps S1131 to S1137 (step S1138). The UE 220 determines whether theTPC command stored in the UL grant received at step S1116 is “00” (stepS1139).

At step S1139, if the TPC command is not “00” (step S1139: NO), the UE220 maintains the TTI bundle size control mode (step S1140), andtransitions to step S1129. If the TPC command is “00” (step S1139: YES),the UE 220 transitions to the transmission power control mode (stepS1141), and transitions to step S1129.

FIGS. 12A and 12B are diagrams depicting another example of changing ofthe TTI bundle size. In FIGS. 12A and 12B, the horizontal axisrepresents time (subframe). In the example depicted in FIG. 12A, at anew transmission 1201, the UE 220 performs TTI bundling (TTI bundlesize=4 TTIs) of transmitting to the eNB 210 successively 4 times,packets representing new data that are the same. The UE 220 performs atretransmissions 1202, 1203, and 1204 concerning the new transmission1201, TTI bundling (TTI bundle size=4 TTIs) of transmitting to the eNB210 successively 4 times, packets representing retransmitted data thatis the same as that at the new transmission 1201.

In the example depicted in FIG. 12B, at the new transmission 1201, theUE 220 performs TTI bundling (TTI bundle size=8 TTIs) of transmitting tothe eNB 210 successively 8 times, packets representing new data that arethe same. At retransmissions 1202, 1203, and 1204 concerning the newtransmission 1201, the UE 220 performs TTI bundling (TTI bundle size=4TTIs) of transmitting to the eNB 210 successively 4 times, packetsrepresenting retransmitted data that is the same as that at the newtransmission 1201.

Under Alt.6.1 of LTE described later, as depicted in FIGS. 12A and 12B,use of TTI bundle sizes differing at a new transmission andretransmission is under consideration. Changing of the TTI bundle sizedescribed above is applicable to changing the TTI bundle size of a newtransmission in a case of using TTI bundle sizes that differ at the newtransmission and retransmission.

For example, the eNB 210 switches the TTI bundle size of a newtransmission of the UE 220 to 4 TTIs and to 8 TTIs and thereby, enablesswitching of the states depicted in FIGS. 12A and 12B. In this manner,configuration may be such that the UE 220 adjusts the TTI bundle size ofdata for a new transmission among a new transmission andretransmissions. Further, here, although a case where the TTI bundlesize of a new transmission is changed among the new transmission andretransmissions, changing of the TTI bundle size of retransmission isidentical.

In this manner, according to the second embodiment, a TPC command of aUL grant used in controlling the transmission power of the UE 220 may beused to give notification of the TTI bundle size of the UE 220. As aresult, the TTI bundle size of the UE 220 may be made variable andincreases in the overhead of control information accompanyingnotification of the TTI bundle size from the eNB 210 to the UE 220 maybe suppressed.

In a third embodiment, portions differing from those of the secondembodiment will be described.

FIGS. 13A and 13B are diagrams depicting examples of changing of theRTT. In FIGS. 13A and 13B, the horizontal axis represents time(subframe). In the example depicted in FIGS. 13A and 13B, at a newtransmission 1301, the UE 220 performs TTI bundling (TTI bundle size=4TTIs) of transmitting to the eNB 210 successively 4 times, packetsrepresenting new data that are the same. Further, at retransmissions1302 to 1305, the UE 220 retransmits successively 4 times, packetsrepresenting retransmitted data that is the same as that at the newtransmission 1301.

In the example depicted in FIG. 13A, the RTT until the retransmissionsis configured to be 16 [ms] (16 subframes). In the example depicted inFIG. 13B, the RTT until the retransmission is configured to be 12 [ms](12 subframes). Further, in the example depicted in FIGS. 13A and 13B,allowed delay is 52 [ms].

Under Alt.1 of LTE described later, as depicted in FIG. 13B, shorteningof the RTT from the current 16 [ms] to 12 [ms] is under consideration.In this regard, in the wireless communications system 200 according tothe third embodiment, the RTT is made variable.

To do this, the eNB 210 uses a control signal to notify the UE 220 ofthe RTT. Here, the eNB 210, for example, uses a TPC command stored inthe UL grant to notify the UE 220 of the RTT. The UE 220 adjusts theRTT, based on the TPC command stored in the UL grant received from theeNB 210.

For example when TTI bundling between the eNB 210 and the UE 220 hasbeen enabled by the control of an higher layer, the eNB 210 and the UE220 enter a state enabling switching to the transmission power controlmode and a TTI bundle size/RTT control mode.

For example, in the transmission power control mode, the UE 220 fixesthe RTT of the UE 220 to 8 [ms] (minimum value). The eNB 210 uses theTPC command to notify the UE 220 of the transmission power. The UE 220adjusts the transmission power of the UE 220, based on the TPC command.

On the other hand, in the TTI bundle size/RTT control mode, the UE 220fixes the transmission power of the UE 220 to a maximum value. The eNB210 uses the TPC command to notify the UE 220 of the RTT. The UE 220adjusts the RTT of the UE 220, based on the TPC command.

In this manner, switching the transmission power control mode of fixingthe RTT and the TTI bundle size/RTT control mode of fixing thetransmission power enables the TPC command for controlling thetransmission power to be further used to control the RTT. As a result,increases in the overhead of control information when the RTT of the UE220 is made variable may be suppressed. Therefore, the RTT may becontrolled according to wireless channel fluctuations and increases inthe overhead of control information may be suppressed.

FIG. 13C is a diagram depicting one example of the total energy oftransmitted packets per unit time. In a unit time N′, the total energyof packets transmitted by a new transmission or retransmission, forexample, is as indicated by a table 1330 in FIG. 13C.

For example, as indicated by (a) in the table 1330, when the TTI bundlesize is 1 and the RTT is 8 [ms], the total energy of packets in a unittime N′ is 3N′/24=N. Here, N is defined as a unit energy for simplicity.Further, as indicated by (b) in the table 1330, when the TTI bundle sizeis 4 and the RTT is 16 [ms], the total energy of packets in a unit timeN′ is 6N′/24=2N, two times that of (a).

As indicated by (c) in the table 1330, when the TTI bundle size is 4 andthe RTT is 12 [ms], the total energy of packets in a unit time N′ is8N′/24=2.67N, 2.67 times that of (a). As indicated by (d) in the table1330, when the TTI bundle size is 4 and the RTT is 8 [ms], the totalenergy of packets in a unit time N′ is 12N′/24=4N, four times that of(a).

FIG. 14A is a diagram depicting a first example of a UL grant bitmap inthe transmission power control mode. A table 1410 depicted in FIG. 14Aindicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the transmission power control mode.

For example, a TPC command=“00” in the transmission power control modeindicates transition to the TTI bundle size/RTT control mode. A TPCcommand=“01” in the transmission power control mode indicates that theTTI bundle size is to be maintained at 1, the RTT is to be maintained at8, and a transmission power increment is to be −1 [dB].

A TPC command=“10” in the transmission power control mode indicates thatthe TTI bundle size is to be maintained at 1, the RTT is to bemaintained at 8, and the transmission power increment is to be 0 [dB](no change). A TPC command=“11” in the transmission power control modeindicates that the TTI bundle size is to be maintained at 1, the RTT isto be maintained at 8, and the transmission power increment is to be 1[dB].

FIG. 14B is a diagram depicting the first example of a UL grant bitmapin the TTI bundle size/RTT control mode. A table 1420 depicted in FIG.14B indicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the TTI bundle size/RTT control mode.

For example, a TPC command=“00” in the TTI bundle size/RTT control modeindicates that the TTI bundle size is to be 1, the RTT is to be 8, andindicates transition to the transmission power control mode. A TPCcommand=“01” in the TTI bundle size/RTT control mode indicates that theTTI bundle size is to be 4 and the RTT is to 16.

A TPC command=“10” in the TTI bundle size/RTT control mode indicatesthat the TTI bundle size is to be 4 and the RTT is to be 12. A TPCcommand=“11” in the TTI bundle size/RTT control mode indicates that theTTI bundle size is to be 4 and the RTT is to be 8.

FIG. 15A is a diagram depicting a second example of a UL grant bitmap inthe transmission power control mode. A table 1510 depicted in FIG. 15Aindicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the transmission power control mode.

For example, a TPC command=“00” in the transmission power control modeindicates that the TTI bundle size is to be maintained at 1, the RTT isto be maintained at 8, and the transmission power increment is to be −1[dB]. A TPC command=“01” in the transmission power control modeindicates that the TTI bundle size is to be maintained at 1, the RTT isto be maintained at 8, and the transmission power increment is to be 0[dB].

A TPC command=“10” in the transmission power control mode indicates thatthe TTI bundle size is to be maintained at 1, the RTT is to bemaintained at 8, and the transmission power increment is to be 1 [dB]. ATPC command=“11” in the transmission power control mode indicates thatthe TTI bundle size is to be maintained at 1, the RTT is to bemaintained at 8, and the transmission power increment is to be 3 [dB].

In this manner, transition to the TTI bundle size/RTT control mode neednot be explicitly notified by a TPC command. In this case, the eNB 210and the UE 220, for example, may determine transition to the TTI bundlesize/RTT control mode, based on PHR. As a result, since the type oftransmission power increment that can be instructed by a TPC commandincreases, more flexible control of the transmission power of the UE 220becomes possible.

For example, the eNB 210 transitions to the TTI bundle size/RTT controlmode, when the PHR received from the UE 220 is 0 or less. Further, theUE 220 transitions to the TTI bundle size/RTT control mode, when the PHRtransmitted to the eNB 210 is 0 or less. As a result, when thetransmission power of the UE 220 reaches the maximum value in thetransmission power control mode, the TTI bundle size/RTT control modemay be transitioned to.

FIG. 15B is a diagram depicting the second example of a UL grant bitmapin the TTI bundle size/RTT control mode. A table 1520 depicted in FIG.15B indicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the TTI bundle size/RTT control mode,i.e., when the transmission power of the UE 220 reaches the maximumvalue (at a time of maximum transmission power). The table 1520 depictedin FIG. 15B, for example, may be the same as the table 1420 depicted inFIG. 14B. Hereinafter, in the third embodiment, a case where the ULgrant bitmap (second example) depicted in FIGS. 15A and 15B is used willbe described.

The transmission power control command setting method in thetransmission power control mode, for example, is identical to thetransmission power control command setting method depicted in FIG. 6A.

FIGS. 16A and 16B are diagrams depicting examples of the transmissionpower control command setting method in the TTI bundle size/RTT controlmode. A table 1610 depicted in FIG. 16A indicates a correspondencerelation of the total energy of transmitted packets per unit timeselected by the eNB 210 and a condition related to the difference Difffrom the targeted value for the measured value of reception SINR, in theTTI bundle size/RTT control mode.

For example, when Diff>4.5 [dB], the eNB 210 selects ¼ times as theadjustment amount of the total energy of transmitted packets per unittime. When 4.5 [dB]≥Diff>1.5 [dB], the eNB 210 selects ½ times as theadjustment amount of the total energy of transmitted packets per unittime.

When 1.5 [dB]≥Diff>−1.5 [dB], the eNB 210 selects 1 time (no change) asthe adjustment amount of the total energy of transmitted packets perunit time. When −1.5 [dB]≥Diff>−4.5 [dB], the eNB 210 selects 2 times asthe adjustment amount of the total energy of transmitted packets perunit time. When −4.5 [dB]≥Diff, the eNB 210 selects 4 times as theadjustment amount of the total energy of transmitted packets per unittime.

A table 1620 depicted in FIG. 16B indicates a correspondence relation ofthe TPC command selected by the eNB 210 and the adjustment result of thetotal energy of transmitted packets per unit time based on the selectedadjustment amount for the total energy of transmitted packets per unittime, in the TTI bundle size/RTT control mode. For example, when theadjustment result<1.5 N, the eNB 210 selects a TPC command=“00”indicating the TTI bundle size=1, RTT=8, and transition to thetransmission power control mode.

When 2.33 N>the adjustment result≥1.5 N, the eNB 210 selects a TPCcommand=“01” indicating the TTI bundle size=4 and RTT=16. When 3.33N>the adjustment result≥2.3 3N, the eNB 210 selects a TPC command=“10”indicating the TTI bundle size=4 and RTT=12. When the adjustmentresult≥3.33 N, the eNB 210 selects a TPC command=“11” indicating the TTIbundle size=4 and RTT=8.

FIG. 17 is a sequence diagram depicting one example of operation of thewireless communications system according to the third embodiment. In thewireless communications system 200 according to the third embodiment,for example, the following steps are performed.

The eNB 210 enables TTI bundling with the UE 220 (step S1701). The eNB210 transmits to the UE 220, an higher layer control signal (TTIbundling=TRUE) instructing TTI bundling to be enabled (step S1702).

The UE 220 enables TTI bundling with the eNB 210 (step S1703). In theexample depicted in FIG. 17, the eNB 210 and the UE 220, which haveenable TTI bundling, are assumed to be in the TTI bundle size/RTTcontrol mode as an initial mode.

The UE 220 transmits a sounding RS to the eNB 210 (step S1704). The eNB210 measures the reception quality based on the sounding RS transmittedat step S1704. The reception quality, for example, is the receptionSINR. In the example depicted in FIG. 17, the eNB 210 is assumed to setthe RTT of the UE 220 to be changed to 8 [ms] and transition to thetransmission power control mode, based on the reception quality measuredat step S1705.

The eNB 210 transmits to the UE 220, a UL grant based on the receptionquality measured at step S1705 (step S1706). The UL grant at step S1706includes the TPC command=“00”. In other words, the UL grant at stepS1706 includes a TPC command instructing the RTT to be configured to 8[ms] and transition to the transmission power control mode (for example,refer to FIG. 15B).

The UE 220 adjusts the TTI bundle size of the UE 220 to 1 TTI and theRTT to 8 [ms], based on the TPC command included in the UL granttransmitted at step S1706 (step S1707). The UE 220 transmits a PUSCH andPHR by a radio resource instructed by the UL grant transmitted at stepS1706 (step S1708). Transmission of the PUSCH at step S1708 is performedby TTI bundling of transmitting the PUSCH one time.

Consequent to step S1706, the eNB 210 and the UE 220 transition to thetransmission power control mode.

The UE 220 transmits a sounding RS to the eNB 210 (step S1709). The eNB210 measures the reception quality based on the sounding RS transmittedat step S1709 (step S1710). In the example depicted in FIG. 17, the eNB210 sets the transmission power of the UE 220 to be increased 3 [dB]based on the reception quality measured at step S1710.

The eNB 210 transmits to the UE 220, a UL grant based on the receptionquality measured at step S1710 (step S1711). The UL grant at step S1711includes the TPC command=“11”. In other words, the UL grant at stepS1711 includes a TPC command instructing the transmission power to beincreased 3 [dB] (for example, refer to FIG. 15A).

The UE 220 performs adjustment such that the transmission powerincreases 3 [dB], based on the TPC command included in the UL granttransmitted at step S1711 (step S1712). Consequent to step S1712, thetransmission power of the UE 220 is assumed to reach the maximumtransmission power. Therefore, the PHR of the UE 220 becomes 0 or less.

The UE 220 transmits a PUSCH and PHR by a radio resource instructed bythe UL grant transmitted at step S1711 (step S1713). Transmission of thePUSCH at step S1713 is performed by TTI bundling of transmitting thePUSCH one time.

Consequent to the PHR of the UE 220 becoming 0 [dB] or less, the eNB 210and the UE 220 transition to the TTI bundle size/RTT control mode.

The UE 220 transmits a sounding RS to the eNB 210 (step S1714). The eNB210 measures the reception quality based on the sounding RS transmittedat step S1714 (step S1715). In the example depicted in FIG. 17, the eNB210 is assumed to set the RTT of the UE 220 to be changed to 16 [ms],based on the reception quality measured at step S1714.

The eNB 210 transmits to the UE 220, a UL grant based on the receptionquality measured at step S1715 (step S1716). The UL grant at step S1716includes the TPC command=“01”. In other words, the UL grant at stepS1716 includes a TPC command instructing the TTI bundle size to beconfigured to 4 and the RTT to be configured to 16 [ms] (for example,refer to FIG. 15B).

The UE 220 adjusts the TTI bundle size to 4 TTIs and the RTT to 16 [ms],based on the TPC command included in the UL grant transmitted at stepS1716 (step S1717). The UE 220 transmits a PUSCH and PHR by a radioresource instructed by the UL grant transmitted at step S1716 (stepS1718). Transmission of the PUSCH at step S1718 is performed by TTIbundling of transmitting successively for 4 TTIs, a PUSCH representingthe same data.

Transmission of the sounding RS at steps S1704, S1709, and S1714, forexample, may be transmission of a periodic sounding RS by the UE 220.

FIG. 18A is a diagram depicting one example of the eNB according to thethird embodiment. FIG. 18B is a diagram depicting one example of signalflow in the eNB depicted in FIG. 18A. In FIGS. 18A and 18B, portionsidentical to those depicted in FIGS. 8A and 8B will be given the samereference numerals used in FIGS. 8A and 8B and description thereof willbe omitted. As depicted in FIGS. 18A and 18B, the eNB 210 according tothe third embodiment includes a TTI bundling/RTT command generating unit1801 in place of the TTI bundling command generating unit 806 depictedin FIGS. 8A and 8B. The TTI bundling/RTT command generating unit 1801,for example, may be realized by the CPU 831 depicted in FIG. 8C.

The TTI bundling/RTT command generating unit 1801 obtains the receptionSINR output from the reception SINR estimating unit 804, in the TTIbundle size/RTT control mode, based on the switching result from themode switching control unit 814. The TTI bundling/RTT command generatingunit 1801 generates a TTI bundling/RTT command for the UE 220 based onthe obtained reception SINR. The TTI bundling command is informationinstructing a TTI bundle size and a RTT. The TTI bundling/RTT commandgenerating unit 1801 outputs the generated TTI bundling/RTT command tothe PUSCH scheduler 807 and the UL grant generating unit 808.

The mode switching control unit 814 begins switching control of the TTIbundle size/RTT control mode and the transmission power control mode,when TTI bundling between the eNB 210 and the UE 220 is enabled.

The control unit 112 depicted in FIGS. 1A and 1B, for example, may berealized by the transmission power control command generating unit 805,the TTI bundling/RTT command generating unit 1801, the UL grantgenerating unit 808, the long-interval reception quality determiningunit 809, and the mode switching control unit 814.

FIG. 19A is a diagram depicting one example of the UE according to thethird embodiment. FIG. 19B is a diagram depicting one example of signalflow in the UE depicted in FIG. 19A. In FIGS. 19A and 19B, portionsidentical to those depicted in FIGS. 9A and 9B are given the samereference numerals used in FIGS. 9A and 9B and description thereof willbe omitted. As depicted in FIGS. 18A and 18B, the third embodiment theUE 220 according to includes a TTI bundling/RTT control unit 1901 inplace of the TTI bundling control unit 907 depicted in FIGS. 9A and 9B.The TTI bundling/RTT control unit 1901, for example, may be realized bythe CPU 931 depicted in FIG. 9C.

The mode switching control unit 905 begins switching control of the TTIbundle size/RTT control mode and the transmission power control mode,when TTI bundling with the eNB 210 is enabled. For example, the modeswitching control unit 905 switches to the TTI bundle size/RTT controlmode from the next transmission, when the PHR output from thetransmission power calculating unit 906 is 0 or less.

The TTI bundling/RTT control unit 1901 obtains the TPC command stored inthe UL grant output from the PDCCH demodulating unit 904, in the TTIbundle size/RTT control mode, based on the switching result output fromthe mode switching control unit 905. The TTI bundling/RTT control unit1901 configures the TTI bundle size and the RTT based on the obtainedTPC command and notifies the PUSCH scheduler 908 of the configured TTIbundle size and RTT.

The PUSCH scheduler 908 performs scheduling of a PUSCH such thatsuccessive transmission and retransmission is performed by the TTIbundle size and RTT output from the TTI bundling/RTT control unit 1901.

The control unit 122 depicted in FIGS. 1A and 1B, for example, may berealized by the mode switching control unit 905, the transmission powercalculating unit 906, and the TTI bundling/RTT control unit 1901.

FIGS. 20A, 20B, and 20C are flowcharts of an example pf processing bythe eNB according to the third embodiment eNB. The eNB 210 according tothe third embodiment, for example, executes the steps depicted in FIGS.20A to 20C. Steps S2001 to S2031 depicted in FIGS. 20A and 20B areidentical to step S1001 to S1031 depicted in FIGS. 10A and 10B. However,at step S2030, the eNB 210 transitions to the TTI bundle size/RTTcontrol mode (step S2030).

At step S2018 the eNB 210 determines whether the current mode is the TTIbundle size/RTT control mode (step S2018). If the mode is not the TTIbundle size/RTT control mode (step S2018: NO), the eNB 210 transitionsto step S2019.

At step S2018, if the current mode is the TTI bundle size/RTT controlmode (step S2018: YES), the eNB 210 transitions to step S2032. In otherwords, the eNB 21 sets the adjustment amount of the total energy oftransmitted packets per unit time of the UE 220, based on the differenceof a predetermined target value and the reception SINR measured at stepS2017 (step S2032).

The eNB 210 determines whether the total energy of transmitted packetsper unit time of the UE 220 after adjustment based on the adjustmentamount set at step S2032 is less than 1.5 N (step S2033). If the totalenergy of transmitted packets per unit time is less than 1.5 N (stepS2033: YES), the eNB 210 configures the TPC command to be “00” (stepS2034), and transitions to step S2040.

At step S2033, if the total energy of transmitted packets per unit timeafter adjustment is not less than 1.5 N (step S2033: NO), the eNB 210determines if the total energy of transmitted packets per unit timeafter adjustment is 1.5 N or greater and less than 2.33 N (step S2035).If the total energy of transmitted packets per unit time afteradjustment is 1.5 N or greater and less than 2.33 N (step S2035: YES),the eNB 210 configures the TPC command to be “01” (step S2036), andtransitions to step S2040.

At step S2035, if the total energy of transmitted packets per unit timeafter adjustment is not 1.5 N or greater and less than 2.33 N (stepS2035: NO), the eNB 210 determines whether the total energy oftransmitted packets per unit time after adjustment is 2.33 N or greaterand less than 3.33 N (step S2037). If the total energy of transmittedpackets per unit time after adjustment is 2.33 N or greater and lessthan 3.33 N (step S2037: YES), the eNB 210 configures the TPC command tobe “10” (step S2038), and transitions to step S2040.

At step S2037, if the total energy of transmitted packets per unit timeafter adjustment is not 2.33 N or greater and less than 3.33 N (stepS2037: NO), the eNB 210 configures the TPC command to be “11” (stepS2039), and transitions to step S2040.

The eNB 210 transmits to the UE 220, the UL grant storing the TPCcommand configured by steps S2033 to S2039 (step S2040). The eNB 210receives a PUSCH from the UE 220, by a radio resource instructed by theUL grant transmitted at step S2040 (step S2041). The eNB 210 determineswhether the TPC command by steps S2033 to S2039 is “00” (step S2042).

At step S2042, if the TPC command is not “00” (step S2042: NO), the eNB210 maintains the TTI bundle size/RTT control mode (step S2043), andtransitions to step S2031. If the TPC command is “00” (step S2042: YES),the eNB 210 transitions to the transmission power control mode (stepS2044), and transitions to step S2031.

FIGS. 21A, 21B, and 21C are flowcharts of an example of processing bythe UE according to the third embodiment UE. The UE 220 according to thethird embodiment, for example, executes the steps depicted in FIGS. 21Ato 21C. Steps S2101 to S2130 depicted in FIGS. 21A and 21B are identicalto steps S1101 to S1130 depicted in FIGS. 11A and 11B. However, at stepS2128, the UE 220 transitions to the TTI bundle size/RTT control mode(step S2128).

Further, at step S2117, the UE 220 determines whether the current modeis the TTI bundle size/RTT control mode (step S2117). If the currentmode is the transmission power control mode and not the TTI bundlesize/RTT control mode (step S2117: NO), the UE 220 transitions to stepS2118. If the current mode is the TTI bundle size/RTT control mode (stepS2117: YES), the UE 220 determines whether the TPC command stored in theUL grant received at step S2116 is “00” (step S2131). If the TPC commandis “00” (step S2131: YES), the UE 220 determines that the TTI bundlesize is 1 and the RTT is 8 (step S2132), and transitions to step S2138.

At step S2131, if the TPC command is not “00” (step S2131: NO), the UE220 determines whether the TPC command is “01” (step S2133). If the TPCcommand is “01” (step S2133: YES), the UE 220 determines that the TTIbundle size is 4 and the RTT is 16 (step S2134), and transitions to stepS2138.

At step S2133, if the TPC command is not “01” (step S2133: NO), the UE220 determines whether the TPC command is “10” (step S2135). If the TPCcommand is “10” (step S2135: YES), the UE 220 determines that the TTIbundle size is 4 and the RTT is (step S2136), and transitions to stepS2138.

At step S2135, if the TPC command is not “10” (step S2135: NO), the UE220 determines that the TTI bundle size is 4 and the RTT is 8 (stepS2137), and transitions to step S2138.

The UE 220 adjusts the TTI bundle size and the RTT by the TTI bundlesize and RTT determined at steps S2131 to S2137 (step S2138). The UE 220determines whether the TPC command stored in the UL grant received atstep S2116 is “00” (step S2139).

At step S2139, if the TPC command is not “00” (step S2139: NO), the UE220 maintains the TTI bundle size/RTT control mode (step S2140), andtransitions to step S2129. If the TPC command is “00” (step S2139: YES),the UE 220 transitions to the transmission power control mode (stepS2141), and transitions to step S2129.

In this manner, according to the third embodiment, a TPC command of a ULgrant used in controlling the transmission power of the UE 220 may beused to give notification of the RTT and the TTI bundle size of the UE220. As a result, the RTT and the TTI bundle size of the UE 220 may bemade variable and increases in the overhead of control informationaccompanying notification of the RTT and the TTI bundle size from theeNB 210 to the UE 220 may be suppressed.

Further, in the TTI bundle size/RTT control mode, although a case wherethe TTI bundle size and the RTT are controlled in combination using aTPC command, configuration may be such that the RTT alone (TTI bundlesize is fixed) is controlled. In this case, the RTT of the UE 220 may bemade variable and increases in the overhead of control informationaccompanying notification of the RTT from the eNB 210 to the UE 220 maybe suppressed.

In a fourth embodiment, portions differing from those of the secondembodiment will be described.

FIG. 22 is a diagram depicting one example of changing a HARQ processcount. In FIG. 22, the horizontal axis represents time (subframe). Inthe example depicted in FIG. 22, the UE 220 performs TTI bundling oftransmitting to the eNB 210 successively four times, packetsrepresenting new data that are the same (transport block #0), by a HARQprocess #0, at a new transmission 2211. The UE 220 performs TTI bundlingof transmitting to the eNB 210 successively four times, packetsrepresenting new data that are the same, by a HARQ process #1, at a newtransmission 2221. The new transmissions 2211, 2221 are transmissions ofnew data that are the same.

At a retransmission 2212, the UE 220 performs TTI bundling oftransmitting to the eNB 210 successively four times, packetsrepresenting data that is the same as that at the new transmission 2211,by the HARQ process #0. At a retransmission 2222, the UE 220 performsTTI bundling of transmitting to the eNB 210 successively four times,packets representing data that is the same as that at the newtransmission 2221, by the HARQ process #1. Therefore, theretransmissions 2212, 2222 are transmissions of the same retransmitteddata.

At a retransmission 2213, the UE 220 performs TTI bundling oftransmitting to the eNB 210 successively four times, packetsrepresenting data that is the same as that at the new transmission 2211,by the HARQ process #0. At a retransmission 2223, the UE 220 performsTTI bundling of transmitting to the eNB 210 successively four times,packets representing data that is the same as that at the newtransmission 2221, by the HARQ process #1. Therefore, retransmissions2213, 2223 are transmissions of the same retransmitted data.

Under Alt.6.2 of LTE described later, as depicted in FIG. 22,transmission of the same signal by (2 processes in the example depictedin FIG. 22) multiple HARQ processes is under consideration. In thisregard, in the wireless communications system 200 according to thefourth embodiment, the HARQ process count is made variable. The HARQprocess count is the number of HARQ processes of transmitting the samedata by TTI bundling, performed with respect to the same data.

To do this, the eNB 210 uses a control signal to notify the UE 220 ofthe HARQ process count. Here, the eNB 210, for example, uses a TPCcommand stored in the UL grant to notify the UE 220 of the HARQ processcount. The UE 220 adjusts the HARQ process count, based on the TPCcommand stored in the UL grant received from the eNB 210. For examplewhen TTI bundling between the eNB 210 and the UE 220 has been enabled bythe control of an higher layer, the eNB 210 and the UE 220 enter a stateenabling switching to the transmission power control mode and a TTIbundle size/the HARQ process count control mode.

For example, in the transmission power control mode, the UE 220 fixesthe HARQ process count of the UE 220 to 1 (minimum value). The eNB 210uses the TPC command to notify the UE 220 of the transmission power. TheUE 220 adjusts the transmission power of the UE 220, based on the TPCcommand.

On the other hand, in the TTI bundle size/the HARQ process count controlmode, the UE 220 fixes the transmission power of the UE 220 to a maximumvalue. The eNB 210 uses the TPC command to notify the UE 220 of the HARQprocess count. The UE 220 adjusts the HARQ process count of the UE 220,based on the TPC command.

In this manner, switching of the transmission power control mode offixing the HARQ process count and the TTI bundle size/the HARQ processcount control mode of fixing the transmission power is enabled.Therefore, the TPC command for controlling the transmission power may befurther used to control the HARQ process count. As a result, increasesin the overhead of control information when the HARQ process count ofthe UE 220 is made variable may be suppressed. Therefore, the HARQprocess count may be controlled according to wireless channelfluctuations and increases in the overhead of control information may besuppressed.

FIG. 23A is a diagram depicting a first example of a UL grant bitmap inthe transmission power control mode. A table 2310 depicted in FIG. 23Aindicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the transmission power control mode.

For example, a TPC command=“00” in the transmission power control modeindicates transition to the TTI bundle size/HARQ process count controlmode. A TPC command=“01” in the transmission power control modeindicates that the TTI bundle size is to be maintained at 1, the RTT isto be maintained at 8, and a transmission power increment is to be −1[dB].

A TPC command=“10” in the transmission power control mode indicates thatthe TTI bundle size is to be maintained at 1 and the transmission powerincrement is to be 0 [dB] (no change). A TPC command=“11” in thetransmission power control mode indicates that the TTI bundle size is tobe maintained at 1 and the transmission power increment is to be 1 [dB].Further, the TCP commands in the transmission power control mode mayfurther indicate that the HARQ process count is maintained at 1.

FIG. 23B is a diagram depicting the first example of a UL grant bitmapin the TTI bundle size/HARQ process count control mode. A table 2320depicted in FIG. 23B indicates a correspondence relation of a TPCcommand and contents notified by the TPC command, in the TTI bundlesize/HARQ process count control mode.

For example, a TPC command=“00” in the TTI bundle size/HARQ processcount control mode indicates that the TTI bundle size is to be 1 andindicates transition to the transmission power control mode. The TPCcommand=“00” in the TTI bundle size/HARQ process count control mode mayfurther indicate that the HARQ process count is maintained at 1.

A TPC command=“10” in the TTI bundle size/HARQ process count controlmode indicates that the TTI bundle size is to be 4 and the HARQ processcount is to be 12. A TPC command=“10” in the TTI bundle size/HARQprocess count control mode indicates that the TTI bundle size is to be 4and the HARQ process count is to be 2. A TPC command=“11” in the TTIbundle size/HARQ process count control mode indicates that the TTIbundle size is to be 4 and the HARQ process count is to be 4.

FIG. 24A is a diagram depicting a second example of a UL grant bitmap inthe transmission power control mode. A table 2410 depicted in FIG. 24Aindicates a correspondence relation of a TPC command and contentsnotified by the TPC command, in the transmission power control mode.

For example, a TPC command=“00” in the transmission power control modeindicates that the TTI bundle size is to be maintained at 1 and thetransmission power increment is to be −1 [dB]. A TPC command=“01” in thetransmission power control mode indicates that the TTI bundle size is tobe maintained at 1 and the transmission power increment is to be 0 [dB].

A TPC command=“10” in the transmission power control mode indicates thatthe TTI bundle size is to be maintained at 1 and the transmission powerincrement is to be 1 [dB]. A TPC command=“11” in the transmission powercontrol mode indicates that the TTI bundle size is to be maintained at 1and the transmission power increment is to be 3 [dB]. Further, the TCPcommands in the transmission power control mode may further indicatethat the HARQ process count is maintained at 1.

In this manner, transition to the TTI bundle size/HARQ process countcontrol mode need not be explicitly notified by a TPC command. In thiscase, the eNB 210 and the UE 220, for example, may determine transitionto the TTI bundle size/HARQ process count control mode, based on PHR. Asa result, since the type of transmission power increment that can beinstructed by a TPC command increases, more flexible control of thetransmission power of the UE 220 becomes possible.

For example, the eNB 210 transitions to the TTI bundle size/HARQ processcount control mode, when the PHR received from the UE 220 is 0 or less.Further, the UE 220 transitions to the TTI bundle size/HARQ processcount control mode, when the PHR transmitted to the eNB 210 is 0 orless. As a result, when the transmission power of the UE 220 reaches themaximum value in the transmission power control mode, the TTI bundlesize/HARQ process count control mode may be transitioned to.

FIG. 24B is a diagram depicting the second example of a UL grant bitmapin the TTI bundle size/HARQ process count control mode. A table 2420depicted in FIG. 24B indicates a correspondence relation of a TPCcommand and contents notified by the TPC command, in the TTI bundlesize/HARQ process count control mode, i.e., when the transmission powerof the UE 220 reaches the maximum value (at a time of maximumtransmission power). The table 2420 depicted in FIG. 24B, for example,may be the same as the table 2320 depicted in FIG. 23B. Hereinafter, inthe fourth embodiment, a case where the UL grant bitmap (second example)depicted in FIGS. 24A and 24B is used will be described.

The transmission power control command setting method in thetransmission power control mode, for example, is identical to thetransmission power control command setting method depicted in FIG. 6A.

FIGS. 25A and 25B are diagrams depicting examples of the transmissionpower control command setting method in the TTI bundle size/the HARQprocess count control mode. A table 2510 depicted in FIG. 25A indicatesa correspondence relation of an adjustment amount of the HARQ processcount selected by the eNB 210 and a condition related to the differenceDiff from the targeted value for the measured value of reception SINR,in the TTI bundle size/the HARQ process count control mode.

For example, when Diff>7.5 [dB], the eNB 210 selects ⅛ times as theadjustment amount of the HARQ process count. When 7.5 [dB]≥Diff>4.5[dB], the eNB 210 selects ¼ times as the adjustment amount of the HARQprocess count. When 4.5 [dB]≥Diff>1.5 [dB], the eNB 210 selects ½ as theadjustment amount of the HARQ process count.

When 1.5 [dB]≥Diff>−1.5 [dB], the eNB 210 selects 1 time (no change) asthe adjustment amount of the HARQ process count. When −1.5[dB]≥Diff>−4.5 [dB], the eNB 210 selects 2 times as the adjustmentamount of the HARQ process count. When −4.5 [dB]≥Diff>−7.5 [dB], the eNB210 selects 4 times as the adjustment amount of the HARQ process count.When −7.5 [dB]≥Diff, the eNB 210 selects 8 times as the adjustmentamount of the HARQ process count.

A table 2520 depicted in FIG. 25B indicates a correspondence relation ofa TPC command selected by the eNB 210 and the adjustment result of theHARQ process count based on the selected adjustment amount of the HARQprocess count, in the TTI bundle size/the HARQ process count controlmode. For example, when the adjustment result<1, the eNB 210 selects theTPC command=“00” indicating the TTI bundle size=1, the HARQ processcount=1, and transitions to the transmission power control mode.

When the adjustment result=1, the eNB 210 selects the TPC command=“01”indicating the TTI bundle size=4 and the HARQ process count=1. When theadjustment result=2, the eNB 210 selects the TPC command=“10” indicatingthe TTI bundle size=4 and the HARQ process count=2. When the adjustmentresult≥4, the eNB 210 selects the TPC command=“11” indicating the TTIbundle size=4 and the HARQ process count=4.

FIG. 26 is a sequence diagram depicting one example of operation of thewireless communications system according to the fourth embodiment. Inthe wireless communications system 200 according to the fourthembodiment, for example, the following steps are performed.

The eNB 210 enables TTI bundling with the UE 220 (step S2601). The eNB210 transmits to the UE 220, an higher layer control signal (TTIbundling=TRUE) instructing TTI bundling to be enabled (step S2602)/

The UE 220 enables TTI bundling with the eNB 210 (step S2603). In theexample depicted in FIG. 26, the eNB 210 and the UE 220, which haveenable TTI bundling, are assumed to be in the TTI bundle size/the HARQprocess count control mode as an initial mode.

The UE 220 transmits a sounding RS to the eNB 210 (step S2604). The eNB210 measures the reception quality based on the sounding RS transmittedat step S2604 (step S2605). The reception quality, for example, is thereception SINR. In the example depicted in FIG. 26, the eNB 210 isassumed to set the HARQ process count of the UE 220 to be changed to 1and transition to the transmission power control mode, based on thereception quality measured at step S2605.

The eNB 210 transmits to the UE 220, a UL grant based on the receptionquality measured at step S2605 (step S2606). The UL grant at step S2606includes the TPC command=“00”. In other words, the UL grant at stepS2606 includes a TPC command instructing the TTI bundle size to beconfigured to 1, the HARQ process count to be configured to 1, andtransition to the transmission power control mode (for example, refer toFIG. 24B).

The UE 220 adjusts the TTI bundle size of the UE 220 to 1 TTI and theHARQ process count to 1, based on the TPC command included in the ULgrant transmitted at step S2606 (step S2607). The UE 220 transmits aPUSCH and PHR by a radio resource instructed by the UL grant transmittedat step S2606 (step S2608). Transmission of the PUSCH at step S2608 isperformed by TTI bundling of transmitting the PUSCH one time.

Consequent to step S2606, the eNB 210 and the UE 220 transition to thetransmission power control mode.

The UE 220 transmits a sounding RS to the eNB 210 (step S2609). The eNB210 measures the reception quality based on the sounding RS transmittedat step S2609 (step S2610). In the example depicted in FIG. 26, the eNB210 sets the transmission power of the UE 220 to be increased 3 [dB]based on the reception quality measured at step S2610.

The eNB 210 transmits to the UE 220, a UL grant based on the receptionquality measured at step S2610 (step S2611). The UL grant at step S2611includes the TPC command=“11”. In other words, the UL grant at stepS2611 includes a TPC command instructing the transmission power to beincreased 3 [dB] (for example, refer to FIG. 24A).

The UE 220 performs adjustment such that the transmission powerincreases 3 [dB], based on the TPC command included in the UL granttransmitted at step S2611 (step S2612). Consequent to step S1712, thetransmission power of the UE 220 is assumed to reach the maximumtransmission power. Therefore, the PHR of the UE 220 becomes 0 or less.

The UE 220 transmits a PUSCH and PHR by a radio resource instructed bythe UL grant transmitted at step S2611 (step S2613). Transmission of thePUSCH at step S2613 is performed by TTI bundling of transmitting thePUSCH one time.

Consequent to the PHR of the UE 220 becoming 0 [dB] or less, the eNB 210and the UE 220 transition to the TTI bundle size/the HARQ process countcontrol mode.

The UE 220 transmits a sounding RS to the eNB 210 (step S2614). The eNB210 The eNB 210 measures the reception quality based on the sounding RStransmitted at step S2614 (step S2615). In the example depicted in FIG.26, the eNB 210 is assumed to set the HARQ process count of the UE 220to be changed to 1, based on the reception quality measured at stepS2614.

The eNB 210 transmits to the UE 220, a UL grant based on the receptionquality measured at step S2615 (step S2616). The UL grant at step S2616includes TPC command=“01”. In other words, the UL grant at step S2616includes a TPC command instructing the TTI bundle size to be configuredto 4 and the HARQ process count to be configured to 1 (for example,refer to FIG. 24B).

The UE 220 adjusts the TTI bundle size to 4 TTIs and the HARQ processcount to 1, based on the TPC command included in the UL granttransmitted at step S2616 (step S2617). The UE 220 transmits a PUSCH andPHR by a radio resource instructed by the UL grant transmitted at stepS2616 (step S2618). Transmission of the PUSCH at step S2618 is performedby TTI bundling of transmitting successively for 4 TTIs, a PUSCHrepresenting the same data.

Transmission of the sounding RS at steps S2604, S2609, and S2614, forexample, may be transmission of a periodic sounding RS by the UE 220.

FIG. 27A is a diagram depicting one example of the eNB according to thefourth embodiment. FIG. 27B is a diagram depicting one example of signalflow in the eNB depicted in FIG. 27A. In FIGS. 27A and 27B, portionsidentical to those depicted in FIGS. 8A and 8B are given the samereference numerals used in FIGS. 8A and 8B and description thereof isomitted. As depicted in FIGS. 27A and 27B, according to the fourthembodiment the eNB 210 includes a TTI bundling/HARQ process countcommand generating unit 2701 in place of the TTI bundling commandgenerating unit 806 depicted in FIGS. 8A and 8B. The TTI bundling/HARQprocess count command generating unit 2701, for example, may be realizedby the CPU 831 depicted in FIG. 8C.

The TTI bundling/HARQ process count command generating unit 2701 obtainsthe reception SINR output from the reception SINR estimating unit 804 inthe TTI bundle size/the HARQ process count control mode, based on aswitching result from the mode switching control unit 814. The TTIbundling/HARQ process count command generating unit 2701 generates a TTIbundling/the HARQ process count command for the UE 220 based on theobtained reception SINR. The TTI bundling/the HARQ process count commandis information instructing a TTI bundle size and a HARQ process count.The TTI bundling/HARQ process count command generating unit 2701 outputsthe generated TTI bundling/the HARQ process count command to the PUSCHscheduler 807 and the UL grant generating unit 808.

The mode switching control unit 814 begins switching control of the TTIbundle size/the HARQ process count control mode and the transmissionpower control mode, when TTI bundling between the eNB 210 and the UE 220is enabled.

The control unit 112 in FIGS. 1A and 1B may be realized by thetransmission power control command generating unit 805, the TTIbundling/HARQ process count command generating unit 2701, the UL grantgenerating unit 808, the long-interval reception quality determiningunit 809, and the mode switching control unit 814.

FIG. 28A is a diagram depicting one example of the UE according to thefourth embodiment. FIG. 28B is a diagram depicting one example of signalflow in the UE depicted in FIG. 28A. In FIGS. 28A and 28B, portionsidentical to those depicted in FIGS. 9A and 9B are given the samereference numerals used in FIGS. 9A and 9B and description thereof isomitted. As depicted in FIGS. 27A and 27B, the UE 220 according to thefourth embodiment includes a TTI bundling/HARQ process count controlunit 2801 in place of the TTI bundling control unit 907 depicted inFIGS. 9A and 9B. The TTI bundling/HARQ process count control unit 2801,for example, may be realized by the CPU 931 depicted in FIG. 9C.

The mode switching control unit 905 begins switching control of the TTIbundle size/the HARQ process count control mode and the transmissionpower control mode, when TTI bundling is enabled with the eNB 210. Forexample, the mode switching control unit 905 switches to the TTI bundlesize/the HARQ process count control mode from the next transmission,when the PHR output from the transmission power calculating unit 906 is0 or less.

The TTI bundling/HARQ process count control unit 2801 sets the TTIbundle size and the HARQ process count, in the TTI bundle size/the HARQprocess count control mode, based on a switching result output from themode switching control unit 905. In particular, the TTI bundling/HARQprocess count control unit 2801 sets the TTI bundle size and the HARQprocess count based on the TPC command stored in the UL grant outputfrom the PDCCH demodulating unit 904. The TTI bundling/HARQ processcount control unit 2801 notifies the PUSCH scheduler 908 of the set TTIbundle size and the HARQ process count.

The PUSCH scheduler 908 performs PUSCH scheduling such that successiveretransmission and HARQ are performed by TTI bundle size and the HARQprocess count output from the TTI bundling/HARQ process count controlunit 2801.

The control unit 122 depicted in FIGS. 1A and 1B, for example, may berealized by the mode switching control unit 905, the transmission powercalculating unit 906, and the TTI bundling/HARQ process count controlunit 2801.

FIGS. 29A, 29B, and 29C are flowcharts of an example of processing bythe eNB according to the fourth embodiment. The eNB 210 according to thefourth embodiment, for example, executes the steps depicted in FIGS. 29Ato 29C. Steps S2901 to S2931 depicted n FIGS. 29A and 29B are identicalto steps S1001 to S1031 depicted in FIGS. 10A to 10B. However, at stepS2930, the eNB 210 transitions to the TTI bundle size/the HARQ processcount control mode (step S2930).

Further, at step S2918, the eNB 210 determines whether the current modeis the TTI bundle size/the HARQ process count control mode (step S2918).If the current mode is not the TTI bundle size/the HARQ process countcontrol mode (step S2918: NO), the eNB 210 transitions to step S2919.

At step S2918, if the current mode is the TTI bundle size/the HARQprocess count control mode (step S2918: YES), the eNB 210 transitions tostep S2932. In other words, the eNB 210 sets the adjustment amount ofthe HARQ process count of the UE 220, based on the difference of thereception SINR measured at step S2917 and a predetermined target value(step S2932).

The eNB 210 determines whether the HARQ process count of the UE 220after adjustment based on the adjustment amount set at step S2932 isless than 1 (step S2933). If the HARQ process count is less than 1 (stepS2933: YES), the eNB 210 configures the TPC command to be “00” (stepS2934), and transitions to step S2940.

At step S2933, if the HARQ process count after adjustment is not 1 orless (step S2933: NO), the eNB 210 determines whether the HARQ processcount after adjustment is 1 (step S2935). If the HARQ process countafter adjustment is 1 (step S2935: YES), the eNB 210 configures the TPCcommand to be “01” (step S2936), and transitions to step S2940.

At step S2935, if the HARQ process count after adjustment is not 1 (stepS2935: NO), the eNB 210 determines whether the HARQ process count afteradjustment is 2 (step S2937). If the HARQ process count after adjustmentis 2 (step S2937: YES), the eNB 210 configures the TPC command to be“10” (step S2938), and transitions to step S2940.

At step S2937, if the HARQ process count after adjusting is not 2 (stepS2937: NO), the eNB 210 configures the TPC command to be “11” (stepS2939), and transitions to step S2940.

The eNB 210 transmits to the UE 220, a UL grant storing the TPC commandconfigured by steps S2933 to S2939 (step S2940). The eNB 210 receives aPUSCH from the UE 220 by a radio resource instructed by the UL granttransmitted at step S2940 (step S2941). The eNB 210 determines whetherthe TPC command configured by steps S2933 to S2939 is “00” (step S2942).

At step S2942, if the TPC command is not “00” (step S2942: NO), the eNB210 maintains the TTI bundle size/the HARQ process count control mode(step S2943), and transitions to step S2931. If the TPC command is “00”(step S2942: YES), the eNB 210 transitions to the transmission powercontrol mode (step S2944), and transitions to step S2931.

FIGS. 30A, 30B, and 30C are flowcharts of an example of processing bythe UE according to the fourth embodiment. The UE 220 according to thefourth embodiment, for example, executes the steps depicted in FIGS. 30Ato 30C. Steps S3001 to S3030 depicted in FIGS. 30A and 30B are identicalto steps S1101 to S1130 depicted in FIGS. 11A and 11B.

However, at step S3028, the UE 220 transitions to the TTI bundlesize/the HARQ process count control mode (step S3028). Further, at stepS3017, the UE 220 determines whether the current mode is the TTI bundlesize/the HARQ process count control mode (step S3017). If the currentmode is the transmission power control mode and not the TTI bundlesize/the HARQ process count control mode (step S3017: NO), the UE 220transitions to step S3018.

At step S3017, if the current mode is the TTI bundle size/the HARQprocess count control mode (step S3017: YES), the UE 220 transitions tostep S3031. In other words, the UE 220 determines whether the TPCcommand stored in the UL grant received at step S3016 is “00” (stepS3031). If the TPC command is “00” (step S3031: YES), the UE 220determines that the TTI bundle size is 1 and the HARQ process count is 1(step S3032), and transitions to step S3038.

At step S3031, if the TPC command is not “00” (step S3031: NO), the UE220 determines whether the TPC command is “01” (step S3033). If the TPCcommand is “01” (step S3033: YES), the UE 220 determines that the TTIbundle size is 4 and the HARQ process count is 1 (step S3034), andtransitions to step S3038.

At step S3033, if the TPC command is not “01” (step S3033: NO), the UE220 determines whether the TPC command is “10” (step S3035). If the TPCcommand is “10” (step S3035: YES), the UE 220 determines that the TTIbundle size is 4 and the HARQ process count is 2 (step S3036), andtransitions to step S3038.

At step S3035, if the TPC command is not “10” (step S3035: NO), the UE220 determines that the TTI bundle size is 4 and the HARQ process countis 4 (step S3037), and transitions to step S3038.

The UE 220 adjusts the TTI bundle size and the HARQ process count by theTTI bundle size and the HARQ process count determined at steps S3031 toS3037 (step S3038). The UE 220 determines whether the TPC command storedin the UL grant received at step S3016 is “00” (step S3039).

At step S3039, if the TPC command is not “00” (step S3039: NO), the UE220 maintains the TTI bundle size/the HARQ process count control mode(step S3040), and transitions to step S3029. If the TPC command is “00”(step S3039: YES), the UE 220 transitions to the transmission powercontrol mode (step S3041), and transitions to step S3029.

In this manner, according to the fourth embodiment, a TPC command of aUL grant used in controlling the transmission power of the UE 220 may beused to give combined notification of the HARQ process count and the TTIbundle size of the UE 220. As a result, the HARQ process count and theTTI bundle size of the UE 220 may be made variable and increases in theoverhead of control information accompanying notification of the TTIbundle size and the HARQ process count from the eNB 210 to the UE 220may be suppressed.

Further, a case of combined control of the TTI bundle size and the HARQprocess count using a TPC command, in the TTI bundle size/the HARQprocess count control mode has been described. In this regard,configuration may be such that the HARQ process count alone (TTI bundlesize is fixed) is controlled. In this case, the HARQ process count ofthe UE 220 may be made variable and increases in the overhead of controlinformation accompanying notification of the HARQ process count from theeNB 210 to the UE 220 may be suppressed.

As described, according to the wireless communications system, the basestation, the terminal, and the process method, a predetermined region ofcontrol information used for transmission power control of the terminalmay be used to give notification of parameters related to uplinkcommunication other than the transmission power of the terminal. As aresult, the parameters may be made variable and increases in theoverhead of control information accompanying notification of theparameters from the base station to the terminal may be suppressed.

For example, techniques of coverage expansion (coverage enhancements) ofLTE are under consideration. For example, as Rel-11 SI, when an LTEsystem independently builds a network, probing of a physical channellimiting coverage characteristics is under consideration (3GPP TR36.824V11.0.0). Further, as Rel-12 WI, coverage enhancement techniques ofULVoIP, etc. are under consideration (3GPP RP-130833).

The contents under consideration are mainly classified as Alt.1,Alt.6.1, Alt.6.2, and Alt.6.3. Alt.1 is reduction of the RTT from 16[ms] to 12 [ms]. As a result, more retransmission packets may besynthesized within the allowed delay period, increasing gain. Alt.6.1 ischanging of the TTI bundle size at a new transmission andretransmission. As a result, the TTI bundle size at a new transmissionmay be increased, whereby gain increases.

Alt.6.2 is use of multiple HARQ processes to transmit 1 transport block.As a result, more retransmission packets may be synthesized within theallowed delay period, increasing gain. Alt.6.3 is making the TTI bundlesize variable according to a control signal. As a result, gain may beadjusted more flexibly.

For example, conventionally, the enabling and disabling of TTI bundlingis switched by a control signal of an higher layer (for example, RLClayer) and therefore, changing configurations consumes time, makingcontrol that follows wireless channel quality difficult.

Therefore, conventionally, for example, in cases where the wirelesschannel quality improves rapidly when TTI bundling is enabled,time-frequency resources may be wasted for excess gain. On the otherhand, in cases where the wireless channel quality rapidly deteriorateswhen TTI bundling is enabled, sufficient gain is not obtained andreception characteristics may degrade. Similarly, concerning the RTT andthe HARQ process count, flexible adjustment cannot be performedcorresponding to the wireless channel quality and therefore,communication cannot be performed efficiently.

In this regard, conceivably, the TTI bundle size, the RTT, the HARQprocess count, etc. may be made variable. However, the overhead ofcontrol information for giving notification of the adjustmentinstruction from the base station to the terminal increases.

According to the embodiments described above, for example, a TPC commandof a UL grant used in controlling the transmission power of the UE 220may be used to further give notification of the TTI bundle size of theUE 22, etc. as well. As a result, the TTI bundle size of the UE 220,etc. may be made variable and increases in the overhead of controlinformation accompanying notification of the TTI bundle size from theeNB 21 to the UE 220 may be suppressed.

Here, for example, when application of TTI bundling is necessary, thetransmission power of the UE 220 has a high possibility of nearlyreaching the maximum transmission power. On the other hand, when thetransmission power of the UE 220 is adjusted, there is a highpossibility that sufficient gain may be obtained without applying TTIbundling. Therefore, merits of concurrently performing control of thetransmission power and control of TTI bundling are few.

In contrast, according to the embodiments described above, for example,one of transmission power and TTI bundle size may be fixed while theother is controlled by a TPC command. As a result, control of thetransmission power and control of the TTI bundle size commonly use theTPC command, enabling increases in the overhead of control informationto be suppressed.

Similarly, merits of concurrently performing control of the transmissionpower and control of RTT are few. In contrast, according to theembodiments described above, for example, one of transmission power andRTT may be fixed while the other is controlled by a TPC command. As aresult, control of the transmission power and control of the RTTcommonly use the TPC command, enabling increases in the overhead ofcontrol information to be suppressed.

Similarly, merits of concurrently performing control of the transmissionpower and control of the HARQ process count are few. In contrast,according to the embodiments described above, for example, one oftransmission power and HARQ process count may be fixed while the otheris controlled by a TPC command. As a result, control of the transmissionpower and control of the HARQ process count commonly use the TPCcommand, enabling increases in the overhead of control information to besuppressed.

Further, with the conventional techniques, for example, when a terminalis able to vary the transmission count of successive transmissions ofthe same data, the overhead of control information accompanyingnotification of the transmission count from the base station to theterminal may increase.

According to one aspect of the present invention, an effect is achievedin that increases in the overhead of control information may besuppressed.

The following notes are further disclosed concerning the embodimentsabove.

(Note 1) A wireless communications system comprising:

a base station configured to switch a first state of storing to apredetermined region of control information transmitted to a terminal, avalue instructing a transmission power of the terminal, and a secondstate of storing to the predetermined region, a value instructing atransmission count of successive transmissions of a same data by theterminal; and

the terminal configured to switch a third state of adjusting thetransmission power based on the value of the predetermined region of thecontrol information received from the base station in the first state,and a fourth state of adjusting the transmission count of successivetransmissions of the same data by the terminal, based on the value ofthe predetermined region of the control information received from thebase station in the second state.

(Note 2) The wireless communications system according to note 1, wherein

the terminal refrains from adjusting the transmission count based on thevalue of the predetermined region when in the third state, and refrainsfrom adjusting the transmission power based on the value of thepredetermined region when in the fourth state.

(Note 3) The wireless communications system according to note 1 or 2,wherein

the base station, when in the first state, stores to the predeterminedregion, a value selected from among a value instructing the transmissionpower and a value instructing switching to the fourth state, and thebase station, when in the second state, stores to the predeterminedregion, a value selected from among a value instructing the transmissioncount and a value instructing switching to the third state,

the terminal transitions to the fourth state and the base stationtransitions to the second state, when the base station stores to thepredetermined region, the value instructing transition to the fourthstate, and

the terminal transitions to the third state and the base stationtransitions to the first state, when the base station stores to thepredetermined region, the value instructing transition to the thirdstate.

(Note 4) The wireless communications system according to note 1 or 2,wherein

the terminal transmits to base station, information that corresponds tothe transmission power of the terminal;

the base station switches to one of the first state and the secondstate, corresponding to the information that corresponds to thetransmission power of the terminal, and

the terminal switches to one of the third state and the fourth state,corresponding to the information that corresponds to the transmissionpower of the terminal.

(Note 5) The wireless communications system according to note 4, wherein

the base station, when in the first state, switches to the second state,when the information that corresponds to the transmission power becomesa predetermined value,

the terminal, when in the third state, switches to the fourth state,when the information that corresponds to the transmission power becomesthe predetermined value,

the base station, when in the second state, stores to the predeterminedregion, a value selected from among a value instructing the transmissioncount and a value instructing switching to the third state, the basestation switching to the first state when the selected value is a valueinstructing switching to the first state, and

the terminal, when in the fourth state, switches to the third state whenthe value of the predetermined region is the value instructing switchingto the third state.

(Note 6) The wireless communications system according to note 4 or 5,wherein

the information that corresponds to the transmission power of theterminal is information indicating a difference of the transmissionpower of the terminal and a maximum transmission power of the terminal.

(Note 7) The wireless communications system according to any one ofnotes 1 to 6, wherein

the terminal adjusts the transmission count concerning a newtransmission among the new transmission and retransmission of data.

(Note 8) The wireless communications system according to any one ofnotes 1 to 6, wherein

the base station, when in the second state, stores to the predeterminedregion, a value indicating a combination of the transmission count and aperiod from when the terminal transmits data until the terminalretransmits the data, and

the terminal, when in the fourth state, adjusts based on the value ofthe predetermined region, the combination of the transmission count andthe period from when the terminal transmits data until the terminalretransmits the data.

(Note 9) The wireless communications system according to any one ofnotes 1 to 7, wherein

the base station, when in the second state, stores to the predeterminedregion, a value indicating a combination of the transmission count and aprocess count of performing for a same data, a process of successivelytransmitting the same data by the terminal, and

the terminal, when in the fourth state, adjusts based on the value ofthe predetermined region, the combination of the transmission count andthe process count of performing for the same data, the process ofsuccessively transmitting the same data by the terminal.

(Note 10) The wireless communications system according to note 9,wherein

the process is a process of hybrid automatic repeat request (HARQ).

(Note 11) The wireless communications system according to any one ofnotes 1 to 10, wherein

the control information is information indicating a radio resourceassigned by the base station to a transmission of a wireless signal fromthe terminal to the base station.

(Note 12) The wireless communications system according to any one ofnotes 1 to 11, wherein

the transmission count of successive transmissions of the same data is atransmission time interval (TTI) bundle size in TTI bundling.

(Note 13) A base station comprising:

a transmitting circuit configured to transmit control information to aterminal; and

a control circuit configured to switch a first state of storing to apredetermined region of the control information transmitted by thetransmitting circuit, a value instructing a transmission power of theterminal, and a second state of storing to the predetermined region, avalue instructing a transmission count of successive transmissions of asame data by the terminal.

(Note 14) A terminal comprising:

a receiving circuit configured to receive control information from abase station configured to switch a first state of storing to apredetermined region of the control information transmitted to theterminal, a value instructing a transmission power of the terminal, anda second state of storing to the predetermined region, a valueinstructing a transmission count of successive transmissions of a samedata by the terminal; and

a control circuit configured to switch a third state of adjusting thetransmission power based on the value of the predetermined region of thecontrol information received from the base station in the first state bythe receiving circuit, and a fourth state of adjusting the transmissioncount of successive transmissions of the same data by the terminal,based on the value of the predetermined region of the controlinformation received from the base station in the second state by thereceiving circuit.

(Note 15) A process method at a base station, the method comprising:

transmitting control information to a terminal; and

switching a first state of storing to a predetermined region of thetransmitted control information, a value instructing a transmissionpower of the terminal, and a second state of storing to thepredetermined region, a value instructing a transmission count ofsuccessive transmissions of a same data by the terminal.

(Note 16) A process method at a terminal, the method comprising:

receiving control information from a base station configured to switch afirst state of storing to a predetermined region of the controlinformation transmitted to the terminal, a value instructing atransmission power of the terminal, and a second state of storing to thepredetermined region, a value instructing a transmission count ofsuccessive transmissions of a same data by the terminal; and

switching a third state of adjusting the transmission power based on thevalue of the predetermined region of the control information receivedfrom the base station in the first state, and a fourth state ofadjusting the transmission count of successive transmissions of the samedata by the terminal, based on the value of the predetermined region ofthe control information received from the base station in the secondstate.

(Note 17) A wireless communications system comprising:

a base station configured to switch a first state of storing to apredetermined region of control information transmitted to a terminal, avalue instructing a transmission power of the terminal, and a secondstate of storing to the predetermined region a value instructing aperiod from when the terminal transmits data until the terminalretransmits the data; and

the terminal configured to switch a third state of adjusting thetransmission power based on the value of the predetermined region of thecontrol information received from the base station in the first state,and a fourth state of adjusting the period from when the terminaltransmits data until the terminal retransmits the data, based on thevalue of the predetermined region of the control information receivedfrom the base station in the second state.

(Note 18) A wireless communications system comprising:

a base station configured to switch a first state of storing to apredetermined region of control information transmitted to a terminal, avalue instructing a transmission power of the terminal, and a secondstate of storing to the predetermined region, a value instructing aprocess count of performing for a same data, a process of successivelytransmitting the same data by the terminal; and

the terminal configured to switch a third state of adjusting thetransmission power based on the value of the predetermined region of thecontrol information received from the base station in the first state,and a fourth state of adjusting the process count of performing for asame data, a process of successively transmitting the same data by theterminal.

All examples and conditional language provided herein are intended forpedagogical purposes of aiding the reader in understanding the inventionand the concepts contributed by the inventor to further the art, and arenot to be construed as limitations to such specifically recited examplesand conditions, nor does the organization of such examples in thespecification relate to a showing of the superiority and inferiority ofthe invention. Although one or more embodiments of the present inventionhave been described in detail, it should be understood that the variouschanges, substitutions, and alterations could be made hereto withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A wireless communications system comprising: abase station configured to switch a first state of storing to controlinformation transmitted to a terminal, a value instructing atransmission power of the terminal, and a second state of storing to thecontrol information, a value instructing a transmission count ofmultiple transmissions of a same data by the terminal; and the terminalconfigured to switch a third state of adjusting the transmission powerbased on the value stored to the control information received from thebase station in the first state, and a fourth state of adjusting thetransmission count of multiple transmissions of the same data by theterminal, based on the value stored to the control information receivedfrom the base station in the second state.
 2. The wirelesscommunications system according to claim 1, wherein the controlinformation includes a predetermined region storing the valueinstructing the transmission power of the terminal, in the first state,and a predetermined region storing the value instructing thetransmission count of multiple transmissions of the same data by theterminal.
 3. The wireless communications system according to claim 1,wherein the terminal refrains from adjusting the transmission power whenin the fourth state.
 4. The wireless communications system according toclaim 1, wherein the base station, when in the first state, stores tothe control information, a value selected from among a value instructingthe transmission power and a value instructing switching to the fourthstate, and the base station, when in the second state, stores to thecontrol information, a value selected from among a value instructing thetransmission count and a value instructing switching to the third state,the terminal transitions to the fourth state and the base stationtransitions to the second state, when the base station stores to thecontrol information, the value instructing transition to the fourthstate, and the terminal transitions to the third state and the basestation transitions to the first state, when the base station stores tothe control information, the value instructing transition to the thirdstate.
 5. The wireless communications system according to claim 1,wherein the terminal transmits to base station, information thatcorresponds to the transmission power of the terminal; the base stationswitches to one of the first state and the second state, correspondingto the information that corresponds to the transmission power of theterminal, and the terminal switches to one of the third state and thefourth state, corresponding to the information that corresponds to thetransmission power of the terminal.
 6. The wireless communicationssystem according to claim 5, wherein the base station, when in the firststate, switches to the second state, when the information thatcorresponds to the transmission power becomes a predetermined value, theterminal, when in the third state, switches to the fourth state, whenthe information that corresponds to the transmission power becomes thepredetermined value, the base station, when in the second state, storesto the control information, a value selected from among a valueinstructing the transmission count and a value instructing switching tothe third state, the base station switching to the first state when theselected value is a value instructing switching to the first state, andthe terminal, when in the fourth state, switches to the third state whenthe value stored to the control information is the value instructingswitching to the third state.
 7. The wireless communications systemaccording to claim 5, wherein the information that corresponds to thetransmission power of the terminal is information indicating adifference of the transmission power of the terminal and a maximumtransmission power of the terminal.
 8. The wireless communicationssystem according to claim 1, wherein the terminal adjusts thetransmission count concerning a new transmission among the newtransmission and retransmission of data.
 9. The wireless communicationssystem according to claim 1, wherein the base station, when in thesecond state, stores to the control information, a value indicating acombination of the transmission count and a period from when theterminal transmits data until retransmission of the data, and theterminal, when in the fourth state, adjusts based on the value stored tothe control information, the combination of the transmission count andthe period from when the terminal transmits data until retransmission ofthe data.
 10. The wireless communications system according to claim 1,wherein the base station, when in the second state, stores to thecontrol information, a value indicating a combination of thetransmission count and a process count of performing for a same data, aprocess of transmitting the same data multiple times, and the terminal,when in the fourth state, adjusts based on the value of thepredetermined region, the combination of the transmission count and theprocess count of performing for the same data, the process oftransmitting the same data multiple times by the terminal.
 11. Thewireless communications system according to claim 10, wherein theprocess is a process of hybrid automatic repeat request (HARQ).
 12. Thewireless communications system according to claim 1, wherein the controlinformation is information indicating a radio resource assigned by thebase station to a transmission of a wireless signal from the terminal tothe base station.
 13. The wireless communications system according toclaim 1, wherein the transmission count of multiple transmissions of thesame data is a transmission time interval (TTI) bundle size in TTIbundling.
 14. A base station comprising: a transmitting circuitconfigured to transmit control information to a terminal; and a controlcircuit configured to switch a first state of storing to a predeterminedregion of the control information transmitted by the transmittingcircuit, a value instructing a transmission power of the terminal, and asecond state of storing to the predetermined region of the controlinformation, a value instructing a transmission count of multipletransmissions of a same data by the terminal.
 15. A terminal comprising:a receiving circuit configured to receive control information from abase station configured to switch a first state of storing to thecontrol information transmitted to the terminal, a value instructing atransmission power of the terminal, and a second state of storing to thecontrol information, a value instructing a transmission count ofmultiple transmissions of a same data by the terminal; and a controlcircuit configured to switch a third state of adjusting the transmissionpower based on the value stored to the control information received fromthe base station in the first state by the receiving circuit, and afourth state of adjusting the transmission count of multipletransmissions of the same data by the terminal, based on the valuestored to the control information received from the base station in thesecond state by the receiving circuit.
 16. The terminal according toclaim 15, wherein the control information includes a predeterminedregion storing the value instructing the transmission power of theterminal, in the first state, and a predetermined region storing thevalue instructing the transmission count of multiple transmissions ofthe same data by the terminal.
 17. A process method at a base station,the method comprising: transmitting control information to a terminal;and switching a first state of storing to a predetermined region of thetransmitted control information, a value instructing a transmissionpower of the terminal, and a second state of storing to thepredetermined region of the control information, a value instructing atransmission count of multiple transmissions of a same data by theterminal.
 18. A process method at a terminal, the method comprising:receiving control information from a base station configured to switch afirst state of storing to the control information transmitted to theterminal, a value instructing a transmission power of the terminal, anda second state of storing to the control information, a valueinstructing a transmission count of multiple transmissions of a samedata by the terminal; and switching a third state of adjusting thetransmission power based on the value stored to the control informationreceived from the base station in the first state, and a fourth state ofadjusting the transmission count of multiple transmissions of the samedata by the terminal, based on the value stored to the controlinformation received from the base station in the second state.
 19. Awireless communications system comprising: a base station configured toswitch a first state of storing to control information transmitted to aterminal, a value instructing a transmission power of the terminal, anda second state of storing to the control information a value instructinga period from when the terminal transmits data until retransmission ofthe data; and the terminal configured to switch a third state ofadjusting the transmission power based on the value stored to thecontrol information received from the base station in the first state,and a fourth state of adjusting the period from when the terminaltransmits data until retransmission of the data, based on the valuestored to the control information received from the base station in thesecond state.
 20. A wireless communications system comprising: a basestation configured to switch a first state of storing to controlinformation transmitted to a terminal, a value instructing atransmission power of the terminal, and a second state of storing to thecontrol information, a value instructing a process count of performingfor a same data, a process of transmitting the same data multiple timesby the terminal; and the terminal configured to switch a third state ofadjusting the transmission power based on the value stored to thecontrol information received from the base station in the first state,and a fourth state of adjusting the process count of performing for asame data, a process of transmitting the same data multiple times by theterminal.